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BUG: KASAN: use-after-free in do_blk_trace_setup+0xa5b/0xad0 kernel/trace/blktrace.c:561
Read of size 8 at addr ffff8880a1376040 by task syz-executor073/6353

CPU: 0 PID: 6353 Comm: syz-executor073 Not tainted 4.14.176-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x13e/0x194 lib/dump_stack.c:58
 print_address_description.cold+0x7c/0x1e2 mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report mm/kasan/report.c:409 [inline]
 kasan_report.cold+0xa9/0x2ae mm/kasan/report.c:393
 do_blk_trace_setup+0xa5b/0xad0 kernel/trace/blktrace.c:561
 blk_trace_setup+0xa3/0x120 kernel/trace/blktrace.c:579
 sg_ioctl+0x2f9/0x2620 drivers/scsi/sg.c:1127
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xfe0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x44aea9
RSP: 002b:00007f3abf214ce8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000006dcc28 RCX: 000000000044aea9
RDX: 0000000020000080 RSI: 00000000c0481273 RDI: 0000000000000004
RBP: 00000000006dcc20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dcc2c
R13: 00007fffbdde4dcf R14: 00007f3abf2159c0 R15: 0000000000000000

Allocated by task 6353:
 save_stack+0x32/0xa0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc mm/kasan/kasan.c:551 [inline]
 kasan_kmalloc+0xbf/0xe0 mm/kasan/kasan.c:529
 kmem_cache_alloc_trace+0x14d/0x7b0 mm/slab.c:3618
 kmalloc include/linux/slab.h:488 [inline]
 kzalloc include/linux/slab.h:661 [inline]
 do_blk_trace_setup+0x11e/0xad0 kernel/trace/blktrace.c:495
 blk_trace_setup+0xa3/0x120 kernel/trace/blktrace.c:579
 sg_ioctl+0x2f9/0x2620 drivers/scsi/sg.c:1127
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xfe0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 6358:
 save_stack+0x32/0xa0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x75/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xcb/0x260 mm/slab.c:3815
 blk_trace_cleanup kernel/trace/blktrace.c:351 [inline]
 blk_trace_remove+0x52/0x80 kernel/trace/blktrace.c:364
 sg_ioctl+0x22a/0x2620 drivers/scsi/sg.c:1136
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xfe0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

The buggy address belongs to the object at ffff8880a1376000
 which belongs to the cache kmalloc-128 of size 128
The buggy address is located 64 bytes inside of
 128-byte region [ffff8880a1376000, ffff8880a1376080)
The buggy address belongs to the page:
page:ffffea000284dd80 count:1 mapcount:0 mapping:ffff8880a1376000 index:0xffff8880a1376b40
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffff8880a1376000 ffff8880a1376b40 0000000100000014
raw: ffffea0002912ca0 ffffea000285ee60 ffff88812fe56640 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a1375f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880a1375f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880a1376000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff8880a1376080: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
 ffff8880a1376100: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
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