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Pull more io_uring fixes from Jens Axboe:
"Two followup fixes. One is fixing a regression from this merge window,
the other is two commits fixing cancelation of deferred requests.
Both have gone through full testing, and both spawned a few new
regression test additions to liburing.
- Don't play games with const, properly store the output iovec and
assign it as needed.
- Deferred request cancelation fix (Pavel)"
* tag 'io_uring-5.9-2020-09-06' of git://git.kernel.dk/linux-block:
io_uring: fix linked deferred ->files cancellation
io_uring: fix cancel of deferred reqs with ->files
io_uring: fix explicit async read/write mapping for large segments
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While looking for ->files in ->defer_list, consider that requests there
may actually be links.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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While trying to cancel requests with ->files, it also should look for
requests in ->defer_list, otherwise it might end up hanging a thread.
Cancel all requests in ->defer_list up to the last request there with
matching ->files, that's needed to follow drain ordering semantics.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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If we exceed UIO_FASTIOV, we don't handle the transition correctly
between an allocated vec for requests that are queued with IOSQE_ASYNC.
Store the iovec appropriately and re-set it in the iter iov in case
it changed.
Fixes: ff6165b2d7f6 ("io_uring: retain iov_iter state over io_read/io_write calls")
Reported-by: Nick Hill <nick@nickhill.org>
Tested-by: Norman Maurer <norman.maurer@googlemail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Pull io_uring fixes from Jens Axboe:
- EAGAIN with O_NONBLOCK retry fix
- Two small fixes for registered files (Jiufei)
* tag 'io_uring-5.9-2020-09-04' of git://git.kernel.dk/linux-block:
io_uring: no read/write-retry on -EAGAIN error and O_NONBLOCK marked file
io_uring: set table->files[i] to NULL when io_sqe_file_register failed
io_uring: fix removing the wrong file in __io_sqe_files_update()
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Actually two things that need fixing up here:
- The io_rw_reissue() -EAGAIN retry is explicit to block devices and
regular files, so don't ever attempt to do that on other types of
files.
- If we hit -EAGAIN on a nonblock marked file, don't arm poll handler for
it. It should just complete with -EAGAIN.
Cc: stable@vger.kernel.org
Reported-by: Norman Maurer <norman.maurer@googlemail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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While io_sqe_file_register() failed in __io_sqe_files_update(),
table->files[i] still point to the original file which may freed
soon, and that will trigger use-after-free problems.
Cc: stable@vger.kernel.org
Fixes: f3bd9dae3708 ("io_uring: fix memleak in __io_sqe_files_update()")
Signed-off-by: Jiufei Xue <jiufei.xue@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Index here is already the position of the file in fixed_file_table, we
should not use io_file_from_index() again to get it. Otherwise, the
wrong file which still in use may be released unexpectedly.
Cc: stable@vger.kernel.org # v5.6
Fixes: 05f3fb3c5397 ("io_uring: avoid ring quiesce for fixed file set unregister and update")
Signed-off-by: Jiufei Xue <jiufei.xue@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Pull io_uring fixes from Jens Axboe:
"A few fixes in here, all based on reports and test cases from folks
using it. Most of it is stable material as well:
- Hashed work cancelation fix (Pavel)
- poll wakeup signalfd fix
- memlock accounting fix
- nonblocking poll retry fix
- ensure we never return -ERESTARTSYS for reads
- ensure offset == -1 is consistent with preadv2() as documented
- IOPOLL -EAGAIN handling fixes
- remove useless task_work bounce for block based -EAGAIN retry"
* tag 'io_uring-5.9-2020-08-28' of git://git.kernel.dk/linux-block:
io_uring: don't bounce block based -EAGAIN retry off task_work
io_uring: fix IOPOLL -EAGAIN retries
io_uring: clear req->result on IOPOLL re-issue
io_uring: make offset == -1 consistent with preadv2/pwritev2
io_uring: ensure read requests go through -ERESTART* transformation
io_uring: don't use poll handler if file can't be nonblocking read/written
io_uring: fix imbalanced sqo_mm accounting
io_uring: revert consumed iov_iter bytes on error
io-wq: fix hang after cancelling pending hashed work
io_uring: don't recurse on tsk->sighand->siglock with signalfd
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These events happen inline from submission, so there's no need to
bounce them through the original task. Just set them up for retry
and issue retry directly instead of going over task_work.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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This normally isn't hit, as polling is mostly done on NVMe with deep
queue depths. But if we do run into request starvation, we need to
ensure that retries are properly serialized.
Reported-by: Andres Freund <andres@anarazel.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Make sure we clear req->result, which was set to -EAGAIN for retry
purposes, when moving it to the reissue list. Otherwise we can end up
retrying a request more than once, which leads to weird results in
the io-wq handling (and other spots).
Cc: stable@vger.kernel.org
Reported-by: Andres Freund <andres@anarazel.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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The man page for io_uring generally claims were consistent with what
preadv2 and pwritev2 accept, but turns out there's a slight discrepancy
in how offset == -1 is handled for pipes/streams. preadv doesn't allow
it, but preadv2 does. This currently causes io_uring to return -EINVAL
if that is attempted, but we should allow that as documented.
This change makes us consistent with preadv2/pwritev2 for just passing
in a NULL ppos for streams if the offset is -1.
Cc: stable@vger.kernel.org # v5.7+
Reported-by: Benedikt Ames <wisp3rwind@posteo.eu>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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We need to call kiocb_done() for any ret < 0 to ensure that we always
get the proper -ERESTARTSYS (and friends) transformation done.
At some point this should be tied into general error handling, so we
can get rid of the various (mostly network) related commands that check
and perform this substitution.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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There's no point in using the poll handler if we can't do a nonblocking
IO attempt of the operation, since we'll need to go async anyway. In
fact this is actively harmful, as reading from eg pipes won't return 0
to indicate EOF.
Cc: stable@vger.kernel.org # v5.7+
Reported-by: Benedikt Ames <wisp3rwind@posteo.eu>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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We do the initial accounting of locked_vm and pinned_vm before we have
setup ctx->sqo_mm, which means we can end up having not accounted the
memory at setup time, but still decrement it when we exit. This causes
an imbalance in the accounting.
Setup ctx->sqo_mm earlier in io_uring_create(), before we do the first
accounting of mm->{locked,pinned}_vm. This also unifies the state
grabbing for the ctx, and eliminates a failure case in
io_sq_offload_start().
Fixes: f74441e6311a ("io_uring: account locked memory before potential error case")
Reported-by: Robert M. Muncrief <rmuncrief@humanavance.com>
Reported-by: Niklas Schnelle <schnelle@linux.ibm.com>
Tested-by: Niklas Schnelle <schnelle@linux.ibm.com>
Tested-by: Robert M. Muncrief <rmuncrief@humanavance.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Some consumers of the iov_iter will return an error, but still have
bytes consumed in the iterator. This is an issue for -EAGAIN, since we
rely on a sane iov_iter state across retries.
Fix this by ensuring that we revert consumed bytes, if any, if the file
operations have consumed any bytes from iterator. This is similar to what
generic_file_read_iter() does, and is always safe as we have the previous
bytes count handy already.
Fixes: ff6165b2d7f6 ("io_uring: retain iov_iter state over io_read/io_write calls")
Reported-by: Dmitry Shulyak <yashulyak@gmail.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.
[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
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If an application is doing reads on signalfd, and we arm the poll handler
because there's no data available, then the wakeup can recurse on the
tasks sighand->siglock as the signal delivery from task_work_add() will
use TWA_SIGNAL and that attempts to lock it again.
We can detect the signalfd case pretty easily by comparing the poll->head
wait_queue_head_t with the target task signalfd wait queue. Just use
normal task wakeup for this case.
Cc: stable@vger.kernel.org # v5.7+
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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If io_import_iovec() returns an error, return iovec is undefined and
must not be used, so don't set it to NULL when failing.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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kfree() handles NULL pointers well, but io_{read,write}() checks it
because of performance reasons. Leave a comment there for those who are
tempted to patch it.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Setting and clearing REQ_F_OVERFLOW in io_uring_cancel_files() and
io_cqring_overflow_flush() are racy, because they might be called
asynchronously.
REQ_F_OVERFLOW flag in only needed for files cancellation, so if it can
be guaranteed that requests _currently_ marked inflight can't be
overflown, the problem will be solved with removing the flag
altogether.
That's how the patch works, it removes inflight status of a request
in io_cqring_fill_event() whenever it should be thrown into CQ-overflow
list. That's Ok to do, because no opcode specific handling can be done
after io_cqring_fill_event(), the same assumption as with "struct
io_completion" patches.
And it already have a good place for such cleanups, which is
io_clean_op(). A nice side effect of this is removing this inflight
check from the hot path.
note on synchronisation: now __io_cqring_fill_event() may be taking two
spinlocks simultaneously, completion_lock and inflight_lock. It's fine,
because we never do that in reverse order, and CQ-overflow of inflight
requests shouldn't happen often.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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We currently use system_wq, which is unbounded in terms of number of
workers. This means that if we're exiting tons of rings at the same
time, then we'll briefly spawn tons of event kworkers just for a very
short blocking time as the rings exit.
Use system_unbound_wq instead, which has a sane cap on the concurrency
level.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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io_rw_prep_async() goes through a dance of clearing req->io, calling
the iovec import, then re-setting req->io. Provide an internal helper
that does the right thing without needing state tweaked to get there.
This enables further cleanups in io_read, io_write, and
io_resubmit_prep(), but that's left for another time.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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The 5.9 merge moved this function io_uring, which means that we don't
need to retain the generic nature of it. Clean up this part by removing
redundant checks, and just inlining the small remainder in
io_rw_should_retry().
No functional changes in this patch.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Commit f254ac04c874 ("io_uring: enable lookup of links holding inflight files")
only handled 2 out of the three head link cases we have, we also need to
lookup and cancel work that is blocked in io-wq if that work has a link
that's holding a reference to the files structure.
Put the "cancel head links that hold this request pending" logic into
io_attempt_cancel(), which will to through the motions of finding and
canceling head links that hold the current inflight files stable request
pending.
Cc: stable@vger.kernel.org
Reported-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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One case was missed in the short IO retry handling, and that's hitting
-EAGAIN on a blocking attempt read (eg from io-wq context). This is a
problem on sockets that are marked as non-blocking when created, they
don't carry any REQ_F_NOWAIT information to help us terminate them
instead of perpetually retrying.
Fixes: 227c0c9673d8 ("io_uring: internally retry short reads")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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There's a bit of confusion on the matching pairs of poll vs double poll,
depending on if the request is a pure poll (IORING_OP_POLL_ADD) or
poll driven retry.
Add io_poll_get_double() that returns the double poll waitqueue, if any,
and io_poll_get_single() that returns the original poll waitqueue. With
that, remove the argument to io_poll_remove_double().
Finally ensure that wait->private is cleared once the double poll handler
has run, so that remove knows it's already been seen.
Cc: stable@vger.kernel.org # v5.8
Reported-by: syzbot+7f617d4a9369028b8a2c@syzkaller.appspotmail.com
Fixes: 18bceab101ad ("io_uring: allow POLL_ADD with double poll_wait() users")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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We've had a few application cases of not handling short reads properly,
and it is understandable as short reads aren't really expected if the
application isn't doing non-blocking IO.
Now that we retain the iov_iter over retries, we can implement internal
retry pretty trivially. This ensures that we don't return a short read,
even for buffered reads on page cache conflicts.
Cleanup the deep nesting and hard to read nature of io_read() as well,
it's much more straight forward now to read and understand. Added a
few comments explaining the logic as well.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Instead of maintaining (and setting/remembering) iov_iter size and
segment counts, just put the iov_iter in the async part of the IO
structure.
This is mostly a preparation patch for doing appropriate internal retries
for short reads, but it also cleans up the state handling nicely and
simplifies it quite a bit.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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When a process exits, we cancel whatever requests it has pending that
are referencing the file table. However, if a link is holding a
reference, then we cannot find it by simply looking at the inflight
list.
Enable checking of the poll and timeout list to find the link, and
cancel it appropriately.
Cc: stable@vger.kernel.org
Reported-by: Josef <josef.grieb@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Check the ipt.error value, it must have been either cleared to zero or
set to another error than the default -EINVAL if we don't go through the
waitqueue proc addition. Just give up on poll at that point and return
failure, this will fallback to async work.
io_poll_add() doesn't suffer from this failure case, as it returns the
error value directly.
Cc: stable@vger.kernel.org # v5.7+
Reported-by: syzbot+a730016dc0bdce4f6ff5@syzkaller.appspotmail.com
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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We're holding the request reference, but we need to go one higher
to ensure that the ctx remains valid after the request has finished.
If the ring is closed with pending task_work inflight, and the
given io_kiocb finishes sync during issue, then we need a reference
to the ring itself around the task_work execution cycle.
Cc: stable@vger.kernel.org # v5.7+
Reported-by: syzbot+9b260fc33297966f5a8e@syzkaller.appspotmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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If we're in the error path failing links and we have a link that has
grabbed a reference to the fs_struct, then we cannot safely drop our
reference to the table if we already hold the completion lock. This
adds a hardirq dependency to the fs_struct->lock, which it currently
doesn't have.
Defer the final cleanup and free of such requests to avoid adding this
dependency.
Reported-by: syzbot+ef4b654b49ed7ff049bf@syzkaller.appspotmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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When we traverse into failing links or timeouts, we need to ensure we
propagate the REQ_F_COMP_LOCKED flag to ensure that we correctly signal
to the completion side that we already hold the completion lock.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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syszbot reports a scenario where we recurse on the completion lock
when flushing an overflow:
1 lock held by syz-executor287/6816:
#0: ffff888093cdb4d8 (&ctx->completion_lock){....}-{2:2}, at: io_cqring_overflow_flush+0xc6/0xab0 fs/io_uring.c:1333
stack backtrace:
CPU: 1 PID: 6816 Comm: syz-executor287 Not tainted 5.8.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1f0/0x31e lib/dump_stack.c:118
print_deadlock_bug kernel/locking/lockdep.c:2391 [inline]
check_deadlock kernel/locking/lockdep.c:2432 [inline]
validate_chain+0x69a4/0x88a0 kernel/locking/lockdep.c:3202
__lock_acquire+0x1161/0x2ab0 kernel/locking/lockdep.c:4426
lock_acquire+0x160/0x730 kernel/locking/lockdep.c:5005
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
_raw_spin_lock_irq+0x67/0x80 kernel/locking/spinlock.c:167
spin_lock_irq include/linux/spinlock.h:379 [inline]
io_queue_linked_timeout fs/io_uring.c:5928 [inline]
__io_queue_async_work fs/io_uring.c:1192 [inline]
__io_queue_deferred+0x36a/0x790 fs/io_uring.c:1237
io_cqring_overflow_flush+0x774/0xab0 fs/io_uring.c:1359
io_ring_ctx_wait_and_kill+0x2a1/0x570 fs/io_uring.c:7808
io_uring_release+0x59/0x70 fs/io_uring.c:7829
__fput+0x34f/0x7b0 fs/file_table.c:281
task_work_run+0x137/0x1c0 kernel/task_work.c:135
exit_task_work include/linux/task_work.h:25 [inline]
do_exit+0x5f3/0x1f20 kernel/exit.c:806
do_group_exit+0x161/0x2d0 kernel/exit.c:903
__do_sys_exit_group+0x13/0x20 kernel/exit.c:914
__se_sys_exit_group+0x10/0x10 kernel/exit.c:912
__x64_sys_exit_group+0x37/0x40 kernel/exit.c:912
do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Fix this by passing back the link from __io_queue_async_work(), and
then let the caller handle the queueing of the link. Take care to also
punt the submission reference put to the caller, as we're holding the
completion lock for the __io_queue_defer() case. Hence we need to mark
the io_kiocb appropriately for that case.
Reported-by: syzbot+996f91b6ec3812c48042@syzkaller.appspotmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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An earlier commit:
b7db41c9e03b ("io_uring: fix regression with always ignoring signals in io_cqring_wait()")
ensured that we didn't get stuck waiting for eventfd reads when it's
registered with the io_uring ring for event notification, but we still
have cases where the task can be waiting on other events in the kernel and
need a bigger nudge to make forward progress. Or the task could be in the
kernel and running, but on its way to blocking.
This means that TWA_RESUME cannot reliably be used to ensure we make
progress. Use TWA_SIGNAL unconditionally.
Cc: stable@vger.kernel.org # v5.7+
Reported-by: Josef <josef.grieb@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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The tear down path will always unaccount the memory, so ensure that we
have accounted it before hitting any of them.
Reported-by: Tomáš Chaloupka <chalucha@gmail.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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If we hit an earlier error path in io_uring_create(), then we will have
accounted memory, but not set ctx->{sq,cq}_entries yet. Then when the
ring is torn down in error, we use those values to unaccount the memory.
Ensure we set the ctx entries before we're able to hit a potential error
path.
Cc: stable@vger.kernel.org
Reported-by: Tomáš Chaloupka <chalucha@gmail.com>
Tested-by: Tomáš Chaloupka <chalucha@gmail.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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loop_rw_iter() does not check whether the file has a read or
write function. This can lead to NULL pointer dereference
when the user passes in a file descriptor that does not have
read or write function.
The crash log looks like this:
[ 99.834071] BUG: kernel NULL pointer dereference, address: 0000000000000000
[ 99.835364] #PF: supervisor instruction fetch in kernel mode
[ 99.836522] #PF: error_code(0x0010) - not-present page
[ 99.837771] PGD 8000000079d62067 P4D 8000000079d62067 PUD 79d8c067 PMD 0
[ 99.839649] Oops: 0010 [#2] SMP PTI
[ 99.840591] CPU: 1 PID: 333 Comm: io_wqe_worker-0 Tainted: G D 5.8.0 #2
[ 99.842622] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1 04/01/2014
[ 99.845140] RIP: 0010:0x0
[ 99.845840] Code: Bad RIP value.
[ 99.846672] RSP: 0018:ffffa1c7c01ebc08 EFLAGS: 00010202
[ 99.848018] RAX: 0000000000000000 RBX: ffff92363bd67300 RCX: ffff92363d461208
[ 99.849854] RDX: 0000000000000010 RSI: 00007ffdbf696bb0 RDI: ffff92363bd67300
[ 99.851743] RBP: ffffa1c7c01ebc40 R08: 0000000000000000 R09: 0000000000000000
[ 99.853394] R10: ffffffff9ec692a0 R11: 0000000000000000 R12: 0000000000000010
[ 99.855148] R13: 0000000000000000 R14: ffff92363d461208 R15: ffffa1c7c01ebc68
[ 99.856914] FS: 0000000000000000(0000) GS:ffff92363dd00000(0000) knlGS:0000000000000000
[ 99.858651] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 99.860032] CR2: ffffffffffffffd6 CR3: 000000007ac66000 CR4: 00000000000006e0
[ 99.861979] Call Trace:
[ 99.862617] loop_rw_iter.part.0+0xad/0x110
[ 99.863838] io_write+0x2ae/0x380
[ 99.864644] ? kvm_sched_clock_read+0x11/0x20
[ 99.865595] ? sched_clock+0x9/0x10
[ 99.866453] ? sched_clock_cpu+0x11/0xb0
[ 99.867326] ? newidle_balance+0x1d4/0x3c0
[ 99.868283] io_issue_sqe+0xd8f/0x1340
[ 99.869216] ? __switch_to+0x7f/0x450
[ 99.870280] ? __switch_to_asm+0x42/0x70
[ 99.871254] ? __switch_to_asm+0x36/0x70
[ 99.872133] ? lock_timer_base+0x72/0xa0
[ 99.873155] ? switch_mm_irqs_off+0x1bf/0x420
[ 99.874152] io_wq_submit_work+0x64/0x180
[ 99.875192] ? kthread_use_mm+0x71/0x100
[ 99.876132] io_worker_handle_work+0x267/0x440
[ 99.877233] io_wqe_worker+0x297/0x350
[ 99.878145] kthread+0x112/0x150
[ 99.878849] ? __io_worker_unuse+0x100/0x100
[ 99.879935] ? kthread_park+0x90/0x90
[ 99.880874] ret_from_fork+0x22/0x30
[ 99.881679] Modules linked in:
[ 99.882493] CR2: 0000000000000000
[ 99.883324] ---[ end trace 4453745f4673190b ]---
[ 99.884289] RIP: 0010:0x0
[ 99.884837] Code: Bad RIP value.
[ 99.885492] RSP: 0018:ffffa1c7c01ebc08 EFLAGS: 00010202
[ 99.886851] RAX: 0000000000000000 RBX: ffff92363acd7f00 RCX: ffff92363d461608
[ 99.888561] RDX: 0000000000000010 RSI: 00007ffe040d9e10 RDI: ffff92363acd7f00
[ 99.890203] RBP: ffffa1c7c01ebc40 R08: 0000000000000000 R09: 0000000000000000
[ 99.891907] R10: ffffffff9ec692a0 R11: 0000000000000000 R12: 0000000000000010
[ 99.894106] R13: 0000000000000000 R14: ffff92363d461608 R15: ffffa1c7c01ebc68
[ 99.896079] FS: 0000000000000000(0000) GS:ffff92363dd00000(0000) knlGS:0000000000000000
[ 99.898017] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 99.899197] CR2: ffffffffffffffd6 CR3: 000000007ac66000 CR4: 00000000000006e0
Fixes: 32960613b7c3 ("io_uring: correctly handle non ->{read,write}_iter() file_operations")
Cc: stable@vger.kernel.org
Signed-off-by: Guoyu Huang <hgy5945@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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The retry based logic here isn't easy to follow unless you're already
familiar with how io_uring does task_work based retries. Add some
comments explaining the flow a little better.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Since we don't do exclusive waits or wakeups, we know that the bit is
always going to be set. Kill the test. Also see commit:
2a9127fcf229 ("mm: rewrite wait_on_page_bit_common() logic")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Pull io_uring updates from Jens Axboe:
"Lots of cleanups in here, hardening the code and/or making it easier
to read and fixing bugs, but a core feature/change too adding support
for real async buffered reads. With the latter in place, we just need
buffered write async support and we're done relying on kthreads for
the fast path. In detail:
- Cleanup how memory accounting is done on ring setup/free (Bijan)
- sq array offset calculation fixup (Dmitry)
- Consistently handle blocking off O_DIRECT submission path (me)
- Support proper async buffered reads, instead of relying on kthread
offload for that. This uses the page waitqueue to drive retries
from task_work, like we handle poll based retry. (me)
- IO completion optimizations (me)
- Fix race with accounting and ring fd install (me)
- Support EPOLLEXCLUSIVE (Jiufei)
- Get rid of the io_kiocb unionizing, made possible by shrinking
other bits (Pavel)
- Completion side cleanups (Pavel)
- Cleanup REQ_F_ flags handling, and kill off many of them (Pavel)
- Request environment grabbing cleanups (Pavel)
- File and socket read/write cleanups (Pavel)
- Improve kiocb_set_rw_flags() (Pavel)
- Tons of fixes and cleanups (Pavel)
- IORING_SQ_NEED_WAKEUP clear fix (Xiaoguang)"
* tag 'for-5.9/io_uring-20200802' of git://git.kernel.dk/linux-block: (127 commits)
io_uring: flip if handling after io_setup_async_rw
fs: optimise kiocb_set_rw_flags()
io_uring: don't touch 'ctx' after installing file descriptor
io_uring: get rid of atomic FAA for cq_timeouts
io_uring: consolidate *_check_overflow accounting
io_uring: fix stalled deferred requests
io_uring: fix racy overflow count reporting
io_uring: deduplicate __io_complete_rw()
io_uring: de-unionise io_kiocb
io-wq: update hash bits
io_uring: fix missing io_queue_linked_timeout()
io_uring: mark ->work uninitialised after cleanup
io_uring: deduplicate io_grab_files() calls
io_uring: don't do opcode prep twice
io_uring: clear IORING_SQ_NEED_WAKEUP after executing task works
io_uring: batch put_task_struct()
tasks: add put_task_struct_many()
io_uring: return locked and pinned page accounting
io_uring: don't miscount pinned memory
io_uring: don't open-code recv kbuf managment
...
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As recently done with with send/recv, flip the if after
rw_verify_aread() in io_{read,write}() and tabulise left bits left.
This removes mispredicted by a compiler jump on the success/fast path.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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As soon as we install the file descriptor, we have to assume that it
can get arbitrarily closed. We currently account memory (and note that
we did) after installing the ring fd, which means that it could be a
potential use-after-free condition if the fd is closed right after
being installed, but before we fiddle with the ctx.
In fact, syzbot reported this exact scenario:
BUG: KASAN: use-after-free in io_account_mem fs/io_uring.c:7397 [inline]
BUG: KASAN: use-after-free in io_uring_create fs/io_uring.c:8369 [inline]
BUG: KASAN: use-after-free in io_uring_setup+0x2797/0x2910 fs/io_uring.c:8400
Read of size 1 at addr ffff888087a41044 by task syz-executor.5/18145
CPU: 0 PID: 18145 Comm: syz-executor.5 Not tainted 5.8.0-rc7-next-20200729-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x18f/0x20d lib/dump_stack.c:118
print_address_description.constprop.0.cold+0xae/0x497 mm/kasan/report.c:383
__kasan_report mm/kasan/report.c:513 [inline]
kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
io_account_mem fs/io_uring.c:7397 [inline]
io_uring_create fs/io_uring.c:8369 [inline]
io_uring_setup+0x2797/0x2910 fs/io_uring.c:8400
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45c429
Code: 8d b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 5b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f8f121d0c78 EFLAGS: 00000246 ORIG_RAX: 00000000000001a9
RAX: ffffffffffffffda RBX: 0000000000008540 RCX: 000000000045c429
RDX: 0000000000000000 RSI: 0000000020000040 RDI: 0000000000000196
RBP: 000000000078bf38 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000078bf0c
R13: 00007fff86698cff R14: 00007f8f121d19c0 R15: 000000000078bf0c
Move the accounting of the ring used locked memory before we get and
install the ring file descriptor.
Cc: stable@vger.kernel.org
Reported-by: syzbot+9d46305e76057f30c74e@syzkaller.appspotmail.com
Fixes: 309758254ea6 ("io_uring: report pinned memory usage")
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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If ->cq_timeouts modifications are done under ->completion_lock, we
don't really nee any fetch-and-add and other complex atomics. Replace it
with non-atomic FAA, that saves an implicit full memory barrier.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Add a helper to mark ctx->{cq,sq}_check_overflow to get rid of
duplicates, and it's clearer to check cq_overflow_list directly anyway.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Always do io_commit_cqring() after completing a request, even if it was
accounted as overflowed on the CQ side. Failing to do that may lead to
not to pushing deferred requests when needed, and so stalling the whole
ring.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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All ->cq_overflow modifications should be under completion_lock,
otherwise it can report a wrong number to the userspace. Fix it in
io_uring_cancel_files().
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Call __io_complete_rw() in io_iopoll_queue() instead of hand coding it.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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