lkml.org 
[lkml]   [2017]   [Jan]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] block: Initialize cfqq->ioprio_class in cfq_get_queue()
From
Date
On 01/23/2017 07:06 AM, Alexander Potapenko wrote:
> KMSAN (KernelMemorySanitizer, a new error detection tool) reports use of
> uninitialized memory in cfq_init_cfqq():
>
> ==================================================================
> BUG: KMSAN: use of unitialized memory
> ...
> Call Trace:
> [< inline >] __dump_stack lib/dump_stack.c:15
> [<ffffffff8202ac97>] dump_stack+0x157/0x1d0 lib/dump_stack.c:51
> [<ffffffff813e9b65>] kmsan_report+0x205/0x360 ??:?
> [<ffffffff813eabbb>] __msan_warning+0x5b/0xb0 ??:?
> [< inline >] cfq_init_cfqq block/cfq-iosched.c:3754
> [<ffffffff8201e110>] cfq_get_queue+0xc80/0x14d0 block/cfq-iosched.c:3857
> ...
> origin:
> [<ffffffff8103ab37>] save_stack_trace+0x27/0x50 arch/x86/kernel/stacktrace.c:67
> [<ffffffff813e836b>] kmsan_internal_poison_shadow+0xab/0x150 ??:?
> [<ffffffff813e88ab>] kmsan_poison_slab+0xbb/0x120 ??:?
> [< inline >] allocate_slab mm/slub.c:1627
> [<ffffffff813e533f>] new_slab+0x3af/0x4b0 mm/slub.c:1641
> [< inline >] new_slab_objects mm/slub.c:2407
> [<ffffffff813e0ef3>] ___slab_alloc+0x323/0x4a0 mm/slub.c:2564
> [< inline >] __slab_alloc mm/slub.c:2606
> [< inline >] slab_alloc_node mm/slub.c:2669
> [<ffffffff813dfb42>] kmem_cache_alloc_node+0x1d2/0x1f0 mm/slub.c:2746
> [<ffffffff8201d90d>] cfq_get_queue+0x47d/0x14d0 block/cfq-iosched.c:3850
> ...
> ==================================================================
> (the line numbers are relative to 4.8-rc6, but the bug persists
> upstream)
>
> The uninitialized struct cfq_queue is created by kmem_cache_alloc_node()
> and then passed to cfq_init_cfqq(), which accesses cfqq->ioprio_class
> before it's initialized.

Patch looks fine to me, thanks. Is this a new warning? We don't seem
to have changed this path in a while, yet I wonder why this is only
surfacing now.

--
Jens Axboe

\
 
 \ /
  Last update: 2017-01-23 16:31    [W:0.116 / U:0.296 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site