From 53a41cb7ed381edee91029cdcabe9b3250f43f4d Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Mon, 25 Feb 2019 09:10:51 -0800 Subject: Revert "x86/fault: BUG() when uaccess helpers fault on kernel addresses" MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This reverts commit 9da3f2b74054406f87dff7101a569217ffceb29b. It was well-intentioned, but wrong. Overriding the exception tables for instructions for random reasons is just wrong, and that is what the new code did. It caused problems for tracing, and it caused problems for strncpy_from_user(), because the new checks made perfectly valid use cases break, rather than catch things that did bad things. Unchecked user space accesses are a problem, but that's not a reason to add invalid checks that then people have to work around with silly flags (in this case, that 'kernel_uaccess_faults_ok' flag, which is just an odd way to say "this commit was wrong" and was sprinked into random places to hide the wrongness). The real fix to unchecked user space accesses is to get rid of the special "let's not check __get_user() and __put_user() at all" logic. Make __{get|put}_user() be just aliases to the regular {get|put}_user() functions, and make it impossible to access user space without having the proper checks in places. The raison d'être of the special double-underscore versions used to be that the range check was expensive, and if you did multiple user accesses, you'd do the range check up front (like the signal frame handling code, for example). But SMAP (on x86) and PAN (on ARM) have made that optimization pointless, because the _real_ expense is the "set CPU flag to allow user space access". Do let's not break the valid cases to catch invalid cases that shouldn't even exist. Cc: Thomas Gleixner Cc: Kees Cook Cc: Tobin C. Harding Cc: Borislav Petkov Cc: Peter Zijlstra Cc: Andy Lutomirski Cc: Jann Horn Signed-off-by: Linus Torvalds --- include/linux/sched.h | 6 ------ 1 file changed, 6 deletions(-) (limited to 'include') diff --git a/include/linux/sched.h b/include/linux/sched.h index bba3afb4e9bf..f9b43c989577 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -739,12 +739,6 @@ struct task_struct { unsigned use_memdelay:1; #endif - /* - * May usercopy functions fault on kernel addresses? - * This is not just a single bit because this can potentially nest. - */ - unsigned int kernel_uaccess_faults_ok; - unsigned long atomic_flags; /* Flags requiring atomic access. */ struct restart_block restart_block; -- cgit v1.2.3 From 46b1c18f9deb326a7e18348e668e4c7ab7c7458b Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 28 Feb 2019 12:55:43 -0800 Subject: net: sched: put back q.qlen into a single location In the series fc8b81a5981f ("Merge branch 'lockless-qdisc-series'") John made the assumption that the data path had no need to read the qdisc qlen (number of packets in the qdisc). It is true when pfifo_fast is used as the root qdisc, or as direct MQ/MQPRIO children. But pfifo_fast can be used as leaf in class full qdiscs, and existing logic needs to access the child qlen in an efficient way. HTB breaks badly, since it uses cl->leaf.q->q.qlen in : htb_activate() -> WARN_ON() htb_dequeue_tree() to decide if a class can be htb_deactivated when it has no more packets. HFSC, DRR, CBQ, QFQ have similar issues, and some calls to qdisc_tree_reduce_backlog() also read q.qlen directly. Using qdisc_qlen_sum() (which iterates over all possible cpus) in the data path is a non starter. It seems we have to put back qlen in a central location, at least for stable kernels. For all qdisc but pfifo_fast, qlen is guarded by the qdisc lock, so the existing q.qlen{++|--} are correct. For 'lockless' qdisc (pfifo_fast so far), we need to use atomic_{inc|dec}() because the spinlock might be not held (for example from pfifo_fast_enqueue() and pfifo_fast_dequeue()) This patch adds atomic_qlen (in the same location than qlen) and renames the following helpers, since we want to express they can be used without qdisc lock, and that qlen is no longer percpu. - qdisc_qstats_cpu_qlen_dec -> qdisc_qstats_atomic_qlen_dec() - qdisc_qstats_cpu_qlen_inc -> qdisc_qstats_atomic_qlen_inc() Later (net-next) we might revert this patch by tracking all these qlen uses and replace them by a more efficient method (not having to access a precise qlen, but an empty/non_empty status that might be less expensive to maintain/track). Another possibility is to have a legacy pfifo_fast version that would be used when used a a child qdisc, since the parent qdisc needs a spinlock anyway. But then, future lockless qdiscs would also have the same problem. Fixes: 7e66016f2c65 ("net: sched: helpers to sum qlen and qlen for per cpu logic") Signed-off-by: Eric Dumazet Cc: John Fastabend Cc: Jamal Hadi Salim Cc: Cong Wang Cc: Jiri Pirko Signed-off-by: David S. Miller --- include/net/sch_generic.h | 31 +++++++++++++------------------ 1 file changed, 13 insertions(+), 18 deletions(-) (limited to 'include') diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h index 9481f2c142e2..e7eb4aa6ccc9 100644 --- a/include/net/sch_generic.h +++ b/include/net/sch_generic.h @@ -51,7 +51,10 @@ struct qdisc_size_table { struct qdisc_skb_head { struct sk_buff *head; struct sk_buff *tail; - __u32 qlen; + union { + u32 qlen; + atomic_t atomic_qlen; + }; spinlock_t lock; }; @@ -408,27 +411,19 @@ static inline void qdisc_cb_private_validate(const struct sk_buff *skb, int sz) BUILD_BUG_ON(sizeof(qcb->data) < sz); } -static inline int qdisc_qlen_cpu(const struct Qdisc *q) -{ - return this_cpu_ptr(q->cpu_qstats)->qlen; -} - static inline int qdisc_qlen(const struct Qdisc *q) { return q->q.qlen; } -static inline int qdisc_qlen_sum(const struct Qdisc *q) +static inline u32 qdisc_qlen_sum(const struct Qdisc *q) { - __u32 qlen = q->qstats.qlen; - int i; + u32 qlen = q->qstats.qlen; - if (q->flags & TCQ_F_NOLOCK) { - for_each_possible_cpu(i) - qlen += per_cpu_ptr(q->cpu_qstats, i)->qlen; - } else { + if (q->flags & TCQ_F_NOLOCK) + qlen += atomic_read(&q->q.atomic_qlen); + else qlen += q->q.qlen; - } return qlen; } @@ -825,14 +820,14 @@ static inline void qdisc_qstats_cpu_backlog_inc(struct Qdisc *sch, this_cpu_add(sch->cpu_qstats->backlog, qdisc_pkt_len(skb)); } -static inline void qdisc_qstats_cpu_qlen_inc(struct Qdisc *sch) +static inline void qdisc_qstats_atomic_qlen_inc(struct Qdisc *sch) { - this_cpu_inc(sch->cpu_qstats->qlen); + atomic_inc(&sch->q.atomic_qlen); } -static inline void qdisc_qstats_cpu_qlen_dec(struct Qdisc *sch) +static inline void qdisc_qstats_atomic_qlen_dec(struct Qdisc *sch) { - this_cpu_dec(sch->cpu_qstats->qlen); + atomic_dec(&sch->q.atomic_qlen); } static inline void qdisc_qstats_cpu_requeues_inc(struct Qdisc *sch) -- cgit v1.2.3 From 6377f787aeb945cae7abbb6474798de129e1f3ac Mon Sep 17 00:00:00 2001 From: YueHaibing Date: Fri, 1 Mar 2019 10:57:57 +0800 Subject: appletalk: Fix use-after-free in atalk_proc_exit KASAN report this: BUG: KASAN: use-after-free in pde_subdir_find+0x12d/0x150 fs/proc/generic.c:71 Read of size 8 at addr ffff8881f41fe5b0 by task syz-executor.0/2806 CPU: 0 PID: 2806 Comm: syz-executor.0 Not tainted 5.0.0-rc7+ #45 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0xfa/0x1ce lib/dump_stack.c:113 print_address_description+0x65/0x270 mm/kasan/report.c:187 kasan_report+0x149/0x18d mm/kasan/report.c:317 pde_subdir_find+0x12d/0x150 fs/proc/generic.c:71 remove_proc_entry+0xe8/0x420 fs/proc/generic.c:667 atalk_proc_exit+0x18/0x820 [appletalk] atalk_exit+0xf/0x5a [appletalk] __do_sys_delete_module kernel/module.c:1018 [inline] __se_sys_delete_module kernel/module.c:961 [inline] __x64_sys_delete_module+0x3dc/0x5e0 kernel/module.c:961 do_syscall_64+0x147/0x600 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x462e99 Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fb2de6b9c58 EFLAGS: 00000246 ORIG_RAX: 00000000000000b0 RAX: ffffffffffffffda RBX: 000000000073bf00 RCX: 0000000000462e99 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000200001c0 RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fb2de6ba6bc R13: 00000000004bccaa R14: 00000000006f6bc8 R15: 00000000ffffffff Allocated by task 2806: set_track mm/kasan/common.c:85 [inline] __kasan_kmalloc.constprop.3+0xa0/0xd0 mm/kasan/common.c:496 slab_post_alloc_hook mm/slab.h:444 [inline] slab_alloc_node mm/slub.c:2739 [inline] slab_alloc mm/slub.c:2747 [inline] kmem_cache_alloc+0xcf/0x250 mm/slub.c:2752 kmem_cache_zalloc include/linux/slab.h:730 [inline] __proc_create+0x30f/0xa20 fs/proc/generic.c:408 proc_mkdir_data+0x47/0x190 fs/proc/generic.c:469 0xffffffffc10c01bb 0xffffffffc10c0166 do_one_initcall+0xfa/0x5ca init/main.c:887 do_init_module+0x204/0x5f6 kernel/module.c:3460 load_module+0x66b2/0x8570 kernel/module.c:3808 __do_sys_finit_module+0x238/0x2a0 kernel/module.c:3902 do_syscall_64+0x147/0x600 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 2806: set_track mm/kasan/common.c:85 [inline] __kasan_slab_free+0x130/0x180 mm/kasan/common.c:458 slab_free_hook mm/slub.c:1409 [inline] slab_free_freelist_hook mm/slub.c:1436 [inline] slab_free mm/slub.c:2986 [inline] kmem_cache_free+0xa6/0x2a0 mm/slub.c:3002 pde_put+0x6e/0x80 fs/proc/generic.c:647 remove_proc_entry+0x1d3/0x420 fs/proc/generic.c:684 0xffffffffc10c031c 0xffffffffc10c0166 do_one_initcall+0xfa/0x5ca init/main.c:887 do_init_module+0x204/0x5f6 kernel/module.c:3460 load_module+0x66b2/0x8570 kernel/module.c:3808 __do_sys_finit_module+0x238/0x2a0 kernel/module.c:3902 do_syscall_64+0x147/0x600 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff8881f41fe500 which belongs to the cache proc_dir_entry of size 256 The buggy address is located 176 bytes inside of 256-byte region [ffff8881f41fe500, ffff8881f41fe600) The buggy address belongs to the page: page:ffffea0007d07f80 count:1 mapcount:0 mapping:ffff8881f6e69a00 index:0x0 flags: 0x2fffc0000000200(slab) raw: 02fffc0000000200 dead000000000100 dead000000000200 ffff8881f6e69a00 raw: 0000000000000000 00000000800c000c 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8881f41fe480: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ffff8881f41fe500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8881f41fe580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881f41fe600: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ffff8881f41fe680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb It should check the return value of atalk_proc_init fails, otherwise atalk_exit will trgger use-after-free in pde_subdir_find while unload the module.This patch fix error cleanup path of atalk_init Reported-by: Hulk Robot Signed-off-by: YueHaibing Signed-off-by: David S. Miller --- include/linux/atalk.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include') diff --git a/include/linux/atalk.h b/include/linux/atalk.h index 23f805562f4e..5a90f28d5ff2 100644 --- a/include/linux/atalk.h +++ b/include/linux/atalk.h @@ -158,7 +158,7 @@ extern int sysctl_aarp_retransmit_limit; extern int sysctl_aarp_resolve_time; #ifdef CONFIG_SYSCTL -extern void atalk_register_sysctl(void); +extern int atalk_register_sysctl(void); extern void atalk_unregister_sysctl(void); #else #define atalk_register_sysctl() do { } while(0) -- cgit v1.2.3