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BUG: KASAN: use-after-free in memset include/linux/string.h:332 [inline]
BUG: KASAN: use-after-free in __ext4_expand_extra_isize.isra.0+0x10b/0x1c0 fs/ext4/inode.c:5795
Write of size 2774 at addr ffff8881b133bca0 by task syz-executor.4/1860

CPU: 1 PID: 1860 Comm: syz-executor.4 Not tainted 4.14.146+ #0
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xca/0x134 lib/dump_stack.c:53
 print_address_description+0x60/0x226 mm/kasan/report.c:187
 __kasan_report.cold+0x1a/0x41 mm/kasan/report.c:316
 memset+0x20/0x40 mm/kasan/common.c:113
 memset include/linux/string.h:332 [inline]
 __ext4_expand_extra_isize.isra.0+0x10b/0x1c0 fs/ext4/inode.c:5795
 ext4_try_to_expand_extra_isize fs/ext4/inode.c:5847 [inline]
 ext4_mark_inode_dirty+0x471/0x7f0 fs/ext4/inode.c:5923
 ext4_rmdir fs/ext4/namei.c:3032 [inline]
 ext4_rmdir+0x8a7/0xbc0 fs/ext4/namei.c:2965
 vfs_rmdir2 fs/namei.c:4032 [inline]
 vfs_rmdir2+0x214/0x410 fs/namei.c:4010
 do_rmdir+0x28a/0x340 fs/namei.c:4098
 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x459797
RSP: 002b:00007ffe56bc4b68 EFLAGS: 00000207 ORIG_RAX: 0000000000000054
RAX: ffffffffffffffda RBX: 0000000000000065 RCX: 0000000000459797
RDX: 0000000000000000 RSI: 0000000000716698 RDI: 00007ffe56bc5ca0
RBP: 0000000000000264 R08: 0000000000000000 R09: 0000000000000001
R10: 000000000000000a R11: 0000000000000207 R12: 00007ffe56bc5ca0
R13: 000055555707f940 R14: 0000000000000000 R15: 00007ffe56bc5ca0

The buggy address belongs to the page:
page:ffffea0006c4cec0 count:2 mapcount:0 mapping:ffff8881da410f10 index:0x429
flags: 0x400000000000203a(referenced|dirty|lru|active|private)
raw: 400000000000203a ffff8881da410f10 0000000000000429 00000002ffffffff
raw: ffffea0006c4e460 ffffea0006c30860 ffff8881c358b1f8 ffff8881da81aa80
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff8881da81aa80

Memory state around the buggy address:
 ffff8881b133bf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8881b133bf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8881b133c000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff8881b133c080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881b133c100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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