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authorAlexander Potapenko <glider@google.com>2017-01-23 15:06:43 +0100
committerJens Axboe <axboe@fb.com>2017-01-23 08:30:28 -0700
commit4d608baac5f4e72b033a122b2d6d9499532c3afc (patch)
tree4cc869d09280f2f09b536efb9cd7719910a2940f /block/cfq-iosched.c
parent70f36b6001bf596eb411c4b302e84c4824ae8730 (diff)
downloadlinux-0-day-4d608baac5f4e72b033a122b2d6d9499532c3afc.tar.gz
block: Initialize cfqq->ioprio_class in cfq_get_queue()
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. Signed-off-by: Alexander Potapenko <glider@google.com> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block/cfq-iosched.c')
-rw-r--r--block/cfq-iosched.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 37aeb20..c472886 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -3864,6 +3864,8 @@ cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
goto out;
}
+ /* cfq_init_cfqq() assumes cfqq->ioprio_class is initialized. */
+ cfqq->ioprio_class = IOPRIO_CLASS_NONE;
cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
cfq_init_prio_data(cfqq, cic);
cfq_link_cfqq_cfqg(cfqq, cfqg);