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BUG: KASAN: use-after-free in memset include/linux/string.h:363 [inline]
BUG: KASAN: use-after-free in __ext4_expand_extra_isize+0x1ab/0x290 fs/ext4/inode.c:5924
Write of size 65536 at addr ffff8880526eb080 by task syz-executor.4/17784

CPU: 1 PID: 17784 Comm: syz-executor.4 Not tainted 5.4.0-rc5+ #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+0x172/0x1f0 lib/dump_stack.c:113
 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374
 __kasan_report.cold+0x1b/0x41 mm/kasan/report.c:506
 kasan_report+0x12/0x20 mm/kasan/common.c:634
 check_memory_region_inline mm/kasan/generic.c:185 [inline]
 check_memory_region+0x134/0x1a0 mm/kasan/generic.c:192
 memset+0x24/0x40 mm/kasan/common.c:105
 memset include/linux/string.h:363 [inline]
 __ext4_expand_extra_isize+0x1ab/0x290 fs/ext4/inode.c:5924
 ext4_try_to_expand_extra_isize fs/ext4/inode.c:5976 [inline]
 ext4_mark_inode_dirty+0x74e/0x9b0 fs/ext4/inode.c:6052
 ext4_ext_tree_init+0x110/0x140 fs/ext4/extents.c:860
 __ext4_new_inode+0x428e/0x4ee0 fs/ext4/ialloc.c:1169
 ext4_symlink+0x45a/0xf10 fs/ext4/namei.c:3262
 vfs_symlink fs/namei.c:4119 [inline]
 vfs_symlink+0x373/0x5a0 fs/namei.c:4105
 do_symlinkat+0x22b/0x290 fs/namei.c:4146
 __do_sys_symlink fs/namei.c:4165 [inline]
 __se_sys_symlink fs/namei.c:4163 [inline]
 __x64_sys_symlink+0x59/0x80 fs/namei.c:4163
 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459c77
Code: 0f 1f 00 b8 5c 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 6d b9 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 b8 58 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 4d b9 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fffbba76278 EFLAGS: 00000206 ORIG_RAX: 0000000000000058
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000459c77
RDX: 00007fffbba76317 RSI: 00000000004bf950 RDI: 00007fffbba76300
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000017
R10: 0000000000000075 R11: 0000000000000206 R12: 0000000000000000
R13: 00007fffbba762b0 R14: 0000000000000000 R15: 00007fffbba762c0

The buggy address belongs to the page:
page:ffffea000149bac0 refcount:2 mapcount:0 mapping:ffff88821a253ae0 index:0x44b
def_blk_aops 
flags: 0x1fffc000000203a(referenced|dirty|lru|active|private)
raw: 01fffc000000203a ffffea00014a0748 ffffea00014ab0c8 ffff88821a253ae0
raw: 000000000000044b ffff88809707f1f8 00000002ffffffff ffff88809517c000
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff88809517c000

Memory state around the buggy address:
 ffff8880526ebf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880526ebf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8880526ec000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff8880526ec080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880526ec100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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