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BUG: KASAN: use-after-free in ext4_ext_rm_leaf fs/ext4/extents.c:2596 [inline]
BUG: KASAN: use-after-free in ext4_ext_remove_space+0x3a6a/0x4920 fs/ext4/extents.c:2934
Read of size 4 at addr ffff888131a63c18 by task syz-executor/487

CPU: 1 PID: 487 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 __dump_stack+0x21/0x24 lib/dump_stack.c:77
 dump_stack_lvl+0x169/0x1d8 lib/dump_stack.c:118
 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:435 [inline]
 kasan_report+0xe2/0x130 mm/kasan/report.c:452
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308
 ext4_ext_rm_leaf fs/ext4/extents.c:2596 [inline]
 ext4_ext_remove_space+0x3a6a/0x4920 fs/ext4/extents.c:2934
 ext4_ext_truncate+0x169/0x1f0 fs/ext4/extents.c:4467
 ext4_truncate+0xaea/0x1290 fs/ext4/inode.c:4367
 ext4_evict_inode+0xf4f/0x1760 fs/ext4/inode.c:290
 evict+0x478/0x910 fs/inode.c:612
 iput_final fs/inode.c:1736 [inline]
 iput+0x638/0x7c0 fs/inode.c:1762
 do_unlinkat+0x33f/0x670 fs/namei.c:4042
 __do_sys_unlink fs/namei.c:4082 [inline]
 __se_sys_unlink fs/namei.c:4080 [inline]
 __x64_sys_unlink+0x49/0x50 fs/namei.c:4080
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f3f9035b577
Code: 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 57 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe3b921ee8 EFLAGS: 00000206 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f3f9035b577
RDX: 00007ffe3b921f10 RSI: 00007ffe3b921fa0 RDI: 00007ffe3b921fa0
RBP: 00007ffe3b921fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000100 R11: 0000000000000206 R12: 00007ffe3b923090
R13: 00007f3f903ded7d R14: 000000000000b737 R15: 00007ffe3b924160

The buggy address belongs to the page:
page:ffffea0004c698c0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x131a63
flags: 0x4000000000000000()
raw: 4000000000000000 ffffea0004c698c8 ffffea0004c698c8 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner info is not present (never set?)

Memory state around the buggy address:
 ffff888131a63b00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888131a63b80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888131a63c00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                            ^
 ffff888131a63c80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888131a63d00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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