2017-01-23 17:06 GMT+03:00 Alexander Potapenko <glider@xxxxxxxxxx>: > 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. > struct cfq_queue is zero initialized (__GFP_ZERO). The warning is false-positive. -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
