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BUG: KASAN: use-after-free in strlen+0x79/0x90 lib/string.c:544
Read of size 1 at addr ffff8881ac0c6208 by task syz-executor.3/9405

CPU: 0 PID: 9405 Comm: syz-executor.3 Not tainted 5.6.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0xef/0x16e lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd3/0x314 mm/kasan/report.c:374
 __kasan_report.cold+0x37/0x77 mm/kasan/report.c:506
 kasan_report+0xe/0x20 mm/kasan/common.c:641
 strlen+0x79/0x90 lib/string.c:544
 strlen include/linux/string.h:303 [inline]
 str_to_user+0x27/0x90 drivers/input/evdev.c:780
 evdev_do_ioctl drivers/input/evdev.c:1183 [inline]
 evdev_ioctl_handler+0x130a/0x19f0 drivers/input/evdev.c:1281
 vfs_ioctl fs/ioctl.c:47 [inline]
 ksys_ioctl+0x11a/0x180 fs/ioctl.c:763
 __do_sys_ioctl fs/ioctl.c:772 [inline]
 __se_sys_ioctl fs/ioctl.c:770 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:770
 do_syscall_64+0xb6/0x5a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c849
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f59043adc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f59043ae6d4 RCX: 000000000045c849
RDX: 00000000200000c0 RSI: 0000000080404507 RDI: 0000000000000003
RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000002ca R14: 00000000004c51be R15: 000000000076bf0c

Allocated by task 8386:
 save_stack+0x1b/0x80 mm/kasan/common.c:72
 set_track mm/kasan/common.c:80 [inline]
 __kasan_kmalloc mm/kasan/common.c:515 [inline]
 __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:488
 kmalloc_array include/linux/slab.h:597 [inline]
 kcalloc include/linux/slab.h:608 [inline]
 alloc_pipe_info+0x1e0/0x4f0 fs/pipe.c:807
 get_pipe_inode fs/pipe.c:871 [inline]
 create_pipe_files+0x8f/0x770 fs/pipe.c:903
 __do_pipe_flags+0x41/0x240 fs/pipe.c:942
 do_pipe2+0x77/0x160 fs/pipe.c:990
 __do_sys_pipe2 fs/pipe.c:1008 [inline]
 __se_sys_pipe2 fs/pipe.c:1006 [inline]
 __x64_sys_pipe2+0x50/0x70 fs/pipe.c:1006
 do_syscall_64+0xb6/0x5a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 8386:
 save_stack+0x1b/0x80 mm/kasan/common.c:72
 set_track mm/kasan/common.c:80 [inline]
 kasan_set_free_info mm/kasan/common.c:337 [inline]
 __kasan_slab_free+0x117/0x160 mm/kasan/common.c:476
 slab_free_hook mm/slub.c:1444 [inline]
 slab_free_freelist_hook mm/slub.c:1477 [inline]
 slab_free mm/slub.c:3024 [inline]
 kfree+0xd5/0x300 mm/slub.c:3976
 free_pipe_info+0x25c/0x310 fs/pipe.c:842
 put_pipe_info+0xb9/0xe0 fs/pipe.c:711
 pipe_release+0x1cc/0x250 fs/pipe.c:734
 __fput+0x2d7/0x840 fs/file_table.c:280
 task_work_run+0x13f/0x1c0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x1d2/0x200 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:278 [inline]
 do_syscall_64+0x4e0/0x5a0 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8881ac0c6000
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 520 bytes inside of
 1024-byte region [ffff8881ac0c6000, ffff8881ac0c6400)
The buggy address belongs to the page:
page:ffffea0006b03000 refcount:1 mapcount:0 mapping:ffff8881da002280 index:0x0 compound_mapcount: 0
flags: 0x200000000010200(slab|head)
raw: 0200000000010200 dead000000000100 dead000000000122 ffff8881da002280
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8881ac0c6100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881ac0c6180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8881ac0c6200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff8881ac0c6280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881ac0c6300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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