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BUG: KASAN: use-after-free in disk_unblock_events+0x51/0x60 block/genhd.c:1550
Read of size 8 at addr ffff8801cdd4d1e0 by task syz-executor410/2104
CPU: 1 PID: 2104 Comm: syz-executor410 Not tainted 4.9.141+ #23
ffff8801cdc0f6e8 ffffffff81b42e79 ffffea0007375200 ffff8801cdd4d1e0
0000000000000000 ffff8801cdd4d1e0 0000000000000000 ffff8801cdc0f720
ffffffff815009b8 ffff8801cdd4d1e0 0000000000000008 0000000000000000
Call Trace:
[<ffffffff81b42e79>] __dump_stack lib/dump_stack.c:15 [inline]
[<ffffffff81b42e79>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
[<ffffffff815009b8>] print_address_description+0x6c/0x234 mm/kasan/report.c:256
[<ffffffff81500dc2>] kasan_report_error mm/kasan/report.c:355 [inline]
[<ffffffff81500dc2>] kasan_report.cold.6+0x242/0x2fe mm/kasan/report.c:412
[<ffffffff814f3074>] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
[<ffffffff81b150c1>] disk_unblock_events+0x51/0x60 block/genhd.c:1550
[<ffffffff815c8f66>] __blkdev_get+0x6b6/0xd60 fs/block_dev.c:1360
[<ffffffff815cb7ea>] blkdev_get+0x2da/0x920 fs/block_dev.c:1416
[<ffffffff815cc045>] blkdev_open+0x1a5/0x250 fs/block_dev.c:1571
[<ffffffff81501e3f>] do_dentry_open+0x3ef/0xc90 fs/open.c:766
[<ffffffff8150576c>] vfs_open+0x11c/0x210 fs/open.c:879
[<ffffffff8153c542>] do_last fs/namei.c:3410 [inline]
[<ffffffff8153c542>] path_openat+0x542/0x2790 fs/namei.c:3534
[<ffffffff81541617>] do_filp_open+0x197/0x270 fs/namei.c:3568
[<ffffffff8150617d>] do_sys_open+0x30d/0x5c0 fs/open.c:1072
[<ffffffff8161882a>] C_SYSC_open fs/compat.c:1081 [inline]
[<ffffffff8161882a>] compat_SyS_open+0x2a/0x40 fs/compat.c:1079
[<ffffffff81006311>] do_syscall_32_irqs_on arch/x86/entry/common.c:328 [inline]
[<ffffffff81006311>] do_fast_syscall_32+0x2f1/0xa10 arch/x86/entry/common.c:390
[<ffffffff82818de0>] entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137
Allocated by task 2104:
save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57
save_stack mm/kasan/kasan.c:505 [inline]
set_track mm/kasan/kasan.c:517 [inline]
kasan_kmalloc.part.1+0x62/0xf0 mm/kasan/kasan.c:609
kasan_kmalloc+0xaf/0xc0 mm/kasan/kasan.c:594
kmem_cache_alloc_trace+0x117/0x2e0 mm/slub.c:2742
kmem_cache_alloc_node_trace include/linux/slab.h:381 [inline]
kmalloc_node include/linux/slab.h:528 [inline]
kzalloc_node include/linux/slab.h:647 [inline]
alloc_disk_node+0x54/0x3a0 block/genhd.c:1294
alloc_disk+0x18/0x20 block/genhd.c:1286
loop_add+0x368/0x7a0 drivers/block/loop.c:1817
loop_control_ioctl+0x136/0x300 drivers/block/loop.c:1949
C_SYSC_ioctl fs/compat_ioctl.c:1602 [inline]
compat_SyS_ioctl+0x12d/0x1fd0 fs/compat_ioctl.c:1549
do_syscall_32_irqs_on arch/x86/entry/common.c:328 [inline]
do_fast_syscall_32+0x2f1/0xa10 arch/x86/entry/common.c:390
entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137
Freed by task 2104:
save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57
save_stack mm/kasan/kasan.c:505 [inline]
set_track mm/kasan/kasan.c:517 [inline]
kasan_slab_free+0xac/0x190 mm/kasan/kasan.c:582
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+0xfb/0x310 mm/slub.c:3878
disk_release+0x259/0x330 block/genhd.c:1147
device_release+0x7e/0x220 drivers/base/core.c:247
kobject_cleanup lib/kobject.c:643 [inline]
kobject_release lib/kobject.c:672 [inline]
kref_sub include/linux/kref.h:73 [inline]
kref_put include/linux/kref.h:98 [inline]
kobject_put+0x148/0x250 lib/kobject.c:689
put_disk+0x23/0x30 block/genhd.c:1358
__blkdev_get+0x616/0xd60 fs/block_dev.c:1353
blkdev_get+0x2da/0x920 fs/block_dev.c:1416
blkdev_open+0x1a5/0x250 fs/block_dev.c:1571
do_dentry_open+0x3ef/0xc90 fs/open.c:766
vfs_open+0x11c/0x210 fs/open.c:879
do_last fs/namei.c:3410 [inline]
path_openat+0x542/0x2790 fs/namei.c:3534
do_filp_open+0x197/0x270 fs/namei.c:3568
do_sys_open+0x30d/0x5c0 fs/open.c:1072
C_SYSC_open fs/compat.c:1081 [inline]
compat_SyS_open+0x2a/0x40 fs/compat.c:1079
do_syscall_32_irqs_on arch/x86/entry/common.c:328 [inline]
do_fast_syscall_32+0x2f1/0xa10 arch/x86/entry/common.c:390
entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137
The buggy address belongs to the object at ffff8801cdd4cc80
which belongs to the cache kmalloc-2048 of size 2048
The buggy address is located 1376 bytes inside of
2048-byte region [ffff8801cdd4cc80, ffff8801cdd4d480)
The buggy address belongs to the page:
page:ffffea0007375200 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0
flags: 0x4000000000004080(slab|head)
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff8801cdd4d080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8801cdd4d100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8801cdd4d180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8801cdd4d200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8801cdd4d280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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