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BUG: KASAN: slab-out-of-bounds in vsscanf+0x2666/0x2ef0 lib/vsprintf.c:3275
Read of size 1 at addr ffff8880919c3286 by task syz-executor.2/8311

CPU: 0 PID: 8311 Comm: syz-executor.2 Not tainted 5.7.0-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+0x1e9/0x30e lib/dump_stack.c:118
 print_address_description+0x74/0x5c0 mm/kasan/report.c:382
 __kasan_report+0x103/0x1a0 mm/kasan/report.c:511
 kasan_report+0x4d/0x80 mm/kasan/common.c:625

Allocated by task 8311:
 save_stack mm/kasan/common.c:49 [inline]
 set_track mm/kasan/common.c:57 [inline]
 __kasan_kmalloc+0x114/0x160 mm/kasan/common.c:495
 __do_kmalloc mm/slab.c:3656 [inline]
 __kmalloc_track_caller+0x249/0x320 mm/slab.c:3671
 memdup_user_nul+0x26/0xf0 mm/util.c:259
 smk_set_cipso+0xff/0x6a0 security/smack/smackfs.c:859
 __vfs_write+0xa7/0x710 fs/read_write.c:495
 vfs_write+0x274/0x580 fs/read_write.c:559
 ksys_write+0x11b/0x220 fs/read_write.c:612
 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff8880919c3280
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 6 bytes inside of
 32-byte region [ffff8880919c3280, ffff8880919c32a0)
The buggy address belongs to the page:
page:ffffea00024670c0 refcount:1 mapcount:0 mapping:0000000048f26b98 index:0xffff8880919c3fc1
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea0002288988 ffffea00022f7c88 ffff8880aa4001c0
raw: ffff8880919c3fc1 ffff8880919c3000 000000010000003f 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880919c3180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880919c3200: fc fc fc fc fc fc fc fc 06 fc fc fc fc fc fc fc
>ffff8880919c3280: 06 fc fc fc fc fc fc fc fb fb fb fb fc fc fc fc
                   ^
 ffff8880919c3300: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8880919c3380: 00 00 00 00 fc fc fc fc 00 00 04 fc fc fc fc fc
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