KASAN: use-after-free Read in snd_seq_queue

Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KASAN: use-after-free Read in snd_seq_queue_alloc	syz			1	2660d	2580d	0/28	closed as invalid on 2017/10/31 12:52
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BUG: KASAN: use-after-free in snd_seq_queue_alloc+0x47e/0x4a0 sound/core/seq/seq_queue.c:202 at addr ffff8801c7622000
Read of size 4 by task syz-executor1/23085
CPU: 1 PID: 23085 Comm: syz-executor1 Not tainted 4.9.40-g7b2727c #16
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801cc49faa8 ffffffff81d8f109 ffff8801da001280 ffff8801c7622000
 ffff8801c7622200 ffffed0038ec4400 ffff8801c7622000 ffff8801cc49fad0
 ffffffff8153931c ffffed0038ec4400 ffff8801da001280 0000000000000000
Call Trace:
 [<ffffffff81d8f109>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d8f109>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff8153931c>] kasan_object_err+0x1c/0x70 mm/kasan/report.c:160
 [<ffffffff815395dc>] print_address_description mm/kasan/report.c:198 [inline]
 [<ffffffff815395dc>] kasan_report_error mm/kasan/report.c:287 [inline]
 [<ffffffff815395dc>] kasan_report.part.1+0x21c/0x500 mm/kasan/report.c:309
 [<ffffffff81539949>] kasan_report mm/kasan/report.c:329 [inline]
 [<ffffffff81539949>] __asan_report_load4_noabort+0x29/0x30 mm/kasan/report.c:329
 [<ffffffff82e096ee>] snd_seq_queue_alloc+0x47e/0x4a0 sound/core/seq/seq_queue.c:202
 [<ffffffff82dfdabd>] snd_seq_ioctl_create_queue+0xad/0x310 sound/core/seq/seq_clientmgr.c:1508
 [<ffffffff82e01146>] snd_seq_ioctl+0x226/0x4a0 sound/core/seq/seq_clientmgr.c:2131
 [<ffffffff815a922a>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<ffffffff815a922a>] do_vfs_ioctl+0x1aa/0x10c0 fs/ioctl.c:679
 [<ffffffff815aa1cf>] SYSC_ioctl fs/ioctl.c:694 [inline]
 [<ffffffff815aa1cf>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
 [<ffffffff838a26c5>] entry_SYSCALL_64_fastpath+0x23/0xc6
Object at ffff8801c7622000, in cache kmalloc-512 size: 512
Allocated:
PID = 23085
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57
 save_stack+0x43/0xd0 mm/kasan/kasan.c:495
 set_track mm/kasan/kasan.c:507 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:598
 kmem_cache_alloc_trace+0xfb/0x2a0 mm/slub.c:2742
 kmalloc include/linux/slab.h:490 [inline]
 kzalloc include/linux/slab.h:636 [inline]
 queue_new sound/core/seq/seq_queue.c:113 [inline]
 snd_seq_queue_alloc+0x5d/0x4a0 sound/core/seq/seq_queue.c:193
 snd_seq_ioctl_create_queue+0xad/0x310 sound/core/seq/seq_clientmgr.c:1508
 snd_seq_ioctl+0x226/0x4a0 sound/core/seq/seq_clientmgr.c:2131
 vfs_ioctl fs/ioctl.c:43 [inline]
 do_vfs_ioctl+0x1aa/0x10c0 fs/ioctl.c:679
 SYSC_ioctl fs/ioctl.c:694 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
 entry_SYSCALL_64_fastpath+0x23/0xc6
Freed:
PID = 23098
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57
 save_stack+0x43/0xd0 mm/kasan/kasan.c:495
 set_track mm/kasan/kasan.c:507 [inline]
 kasan_slab_free+0x73/0xc0 mm/kasan/kasan.c:571
 slab_free_hook mm/slub.c:1355 [inline]
 slab_free_freelist_hook mm/slub.c:1377 [inline]
 slab_free mm/slub.c:2958 [inline]
 kfree+0xf0/0x2f0 mm/slub.c:3878
 queue_delete+0x90/0xb0 sound/core/seq/seq_queue.c:156
 snd_seq_queue_delete+0x3c/0x50 sound/core/seq/seq_queue.c:215
 snd_seq_ioctl_delete_queue+0x6a/0x90 sound/core/seq/seq_clientmgr.c:1534
 snd_seq_ioctl+0x226/0x4a0 sound/core/seq/seq_clientmgr.c:2131
 vfs_ioctl fs/ioctl.c:43 [inline]
 do_vfs_ioctl+0x1aa/0x10c0 fs/ioctl.c:679
 SYSC_ioctl fs/ioctl.c:694 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
 entry_SYSCALL_64_fastpath+0x23/0xc6
Memory state around the buggy address:
 ffff8801c7621f00: fb fb fb fb fb fb fb fb fc fc fc fc fb fb fb fb
 ffff8801c7621f80: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8801c7622000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff8801c7622080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801c7622100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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