From 16238415eb9886328a89fe7a3cb0b88c7335fe16 Mon Sep 17 00:00:00 2001 From: Luo Meng Date: Fri, 23 Oct 2020 14:20:05 +0800 Subject: locks: Fix UBSAN undefined behaviour in flock64_to_posix_lock When the sum of fl->fl_start and l->l_len overflows, UBSAN shows the following warning: UBSAN: Undefined behaviour in fs/locks.c:482:29 signed integer overflow: 2 + 9223372036854775806 cannot be represented in type 'long long int' Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0xe4/0x14e lib/dump_stack.c:118 ubsan_epilogue+0xe/0x81 lib/ubsan.c:161 handle_overflow+0x193/0x1e2 lib/ubsan.c:192 flock64_to_posix_lock fs/locks.c:482 [inline] flock_to_posix_lock+0x595/0x690 fs/locks.c:515 fcntl_setlk+0xf3/0xa90 fs/locks.c:2262 do_fcntl+0x456/0xf60 fs/fcntl.c:387 __do_sys_fcntl fs/fcntl.c:483 [inline] __se_sys_fcntl fs/fcntl.c:468 [inline] __x64_sys_fcntl+0x12d/0x180 fs/fcntl.c:468 do_syscall_64+0xc8/0x5a0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe Fix it by parenthesizing 'l->l_len - 1'. Signed-off-by: Luo Meng Signed-off-by: Jeff Layton --- fs/locks.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs') diff --git a/fs/locks.c b/fs/locks.c index 1f84a03601fe..bc08610bae2f 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -542,7 +542,7 @@ static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl, if (l->l_len > 0) { if (l->l_len - 1 > OFFSET_MAX - fl->fl_start) return -EOVERFLOW; - fl->fl_end = fl->fl_start + l->l_len - 1; + fl->fl_end = fl->fl_start + (l->l_len - 1); } else if (l->l_len < 0) { if (fl->fl_start + l->l_len < 0) -- cgit v1.2.3 From 529adfe8f131c60938ece113379f1a07640aefb1 Mon Sep 17 00:00:00 2001 From: Mauro Carvalho Chehab Date: Fri, 23 Oct 2020 18:33:23 +0200 Subject: locks: fix a typo at a kernel-doc markup locks_delete_lock -> locks_delete_block Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Jeff Layton --- fs/locks.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs') diff --git a/fs/locks.c b/fs/locks.c index bc08610bae2f..ed95cd813e10 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -750,7 +750,7 @@ static void __locks_wake_up_blocks(struct file_lock *blocker) } /** - * locks_delete_lock - stop waiting for a file lock + * locks_delete_block - stop waiting for a file lock * @waiter: the lock which was waiting * * lockd/nfsd need to disconnect the lock while working on it. -- cgit v1.2.3 From 8d1ddb5e79374fb277985a6b3faa2ed8631c5b4c Mon Sep 17 00:00:00 2001 From: Boqun Feng Date: Thu, 5 Nov 2020 14:23:51 +0800 Subject: fcntl: Fix potential deadlock in send_sig{io, urg}() Syzbot reports a potential deadlock found by the newly added recursive read deadlock detection in lockdep: [...] ======================================================== [...] WARNING: possible irq lock inversion dependency detected [...] 5.9.0-rc2-syzkaller #0 Not tainted [...] -------------------------------------------------------- [...] syz-executor.1/10214 just changed the state of lock: [...] ffff88811f506338 (&f->f_owner.lock){.+..}-{2:2}, at: send_sigurg+0x1d/0x200 [...] but this lock was taken by another, HARDIRQ-safe lock in the past: [...] (&dev->event_lock){-...}-{2:2} [...] [...] [...] and interrupts could create inverse lock ordering between them. [...] [...] [...] other info that might help us debug this: [...] Chain exists of: [...] &dev->event_lock --> &new->fa_lock --> &f->f_owner.lock [...] [...] Possible interrupt unsafe locking scenario: [...] [...] CPU0 CPU1 [...] ---- ---- [...] lock(&f->f_owner.lock); [...] local_irq_disable(); [...] lock(&dev->event_lock); [...] lock(&new->fa_lock); [...] [...] lock(&dev->event_lock); [...] [...] *** DEADLOCK *** The corresponding deadlock case is as followed: CPU 0 CPU 1 CPU 2 read_lock(&fown->lock); spin_lock_irqsave(&dev->event_lock, ...) write_lock_irq(&filp->f_owner.lock); // wait for the lock read_lock(&fown-lock); // have to wait until the writer release // due to the fairness spin_lock_irqsave(&dev->event_lock); // wait for the lock The lock dependency on CPU 1 happens if there exists a call sequence: input_inject_event(): spin_lock_irqsave(&dev->event_lock,...); input_handle_event(): input_pass_values(): input_to_handler(): handler->event(): // evdev_event() evdev_pass_values(): spin_lock(&client->buffer_lock); __pass_event(): kill_fasync(): kill_fasync_rcu(): read_lock(&fa->fa_lock); send_sigio(): read_lock(&fown->lock); To fix this, make the reader in send_sigurg() and send_sigio() use read_lock_irqsave() and read_lock_irqrestore(). Reported-by: syzbot+22e87cdf94021b984aa6@syzkaller.appspotmail.com Reported-by: syzbot+c5e32344981ad9f33750@syzkaller.appspotmail.com Signed-off-by: Boqun Feng Signed-off-by: Jeff Layton --- fs/fcntl.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) (limited to 'fs') diff --git a/fs/fcntl.c b/fs/fcntl.c index 19ac5baad50f..05b36b28f2e8 100644 --- a/fs/fcntl.c +++ b/fs/fcntl.c @@ -781,9 +781,10 @@ void send_sigio(struct fown_struct *fown, int fd, int band) { struct task_struct *p; enum pid_type type; + unsigned long flags; struct pid *pid; - read_lock(&fown->lock); + read_lock_irqsave(&fown->lock, flags); type = fown->pid_type; pid = fown->pid; @@ -804,7 +805,7 @@ void send_sigio(struct fown_struct *fown, int fd, int band) read_unlock(&tasklist_lock); } out_unlock_fown: - read_unlock(&fown->lock); + read_unlock_irqrestore(&fown->lock, flags); } static void send_sigurg_to_task(struct task_struct *p, @@ -819,9 +820,10 @@ int send_sigurg(struct fown_struct *fown) struct task_struct *p; enum pid_type type; struct pid *pid; + unsigned long flags; int ret = 0; - read_lock(&fown->lock); + read_lock_irqsave(&fown->lock, flags); type = fown->pid_type; pid = fown->pid; @@ -844,7 +846,7 @@ int send_sigurg(struct fown_struct *fown) read_unlock(&tasklist_lock); } out_unlock_fown: - read_unlock(&fown->lock); + read_unlock_irqrestore(&fown->lock, flags); return ret; } -- cgit v1.2.3