==================================================================
BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:827 [inline]
BUG: KASAN: use-after-free in ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:946
Read of size 4 at addr ffff88812ee42ec4 by task kworker/u4:1/10

CPU: 1 PID: 10 Comm: kworker/u4:1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: writeback wb_workfn (flush-7:2)
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:88
 dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106
 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:427 [inline]
 kasan_report+0xf1/0x140 mm/kasan/report.c:444
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308
 ext4_ext_binsearch fs/ext4/extents.c:827 [inline]
 ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:946
 ext4_ext_map_blocks+0x207/0x61e0 fs/ext4/extents.c:4166
 ext4_map_blocks+0x988/0x1b30 fs/ext4/inode.c:674
 mpage_map_one_extent fs/ext4/inode.c:2421 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2474 [inline]
 ext4_writepages+0x123f/0x3090 fs/ext4/inode.c:2842
 do_writepages+0x473/0x6c0 mm/page-writeback.c:2388
 __writeback_single_inode+0xd5/0x9c0 fs/fs-writeback.c:1657
 writeback_sb_inodes+0xa10/0x1610 fs/fs-writeback.c:1940
 wb_writeback+0x40b/0x9d0 fs/fs-writeback.c:2116
 wb_do_writeback fs/fs-writeback.c:2263 [inline]
 wb_workfn+0x3ac/0xf30 fs/fs-writeback.c:2304
 process_one_work+0x6be/0xba0 kernel/workqueue.c:2325
 worker_thread+0xa59/0x1200 kernel/workqueue.c:2472
 kthread+0x411/0x500 kernel/kthread.c:337
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

The buggy address belongs to the page:
page:ffffea0004bb9080 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x12ee42
flags: 0x4000000000000000(zone=1)
raw: 4000000000000000 ffffea0004bb90c8 ffffea0004bb9048 0000000000000000
raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner info is not present (never set?)

Memory state around the buggy address:
 ffff88812ee42d80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88812ee42e00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88812ee42e80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                           ^
 ffff88812ee42f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88812ee42f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
EXT4-fs error (device loop2): __ext4_get_inode_loc:4358: comm kworker/u4:1: Invalid inode table block 8391460049216894068 in block_group 0
EXT4-fs error (device loop2) in ext4_reserve_inode_write:5881: Corrupt filesystem
EXT4-fs error (device loop2): ext4_dirty_inode:6085: inode #15: comm kworker/u4:1: mark_inode_dirty error
EXT4-fs error (device loop2): ext4_read_block_bitmap_nowait:476: comm kworker/u4:1: Invalid block bitmap block 8391460049216894068 in block_group 0
EXT4-fs error (device loop2): __ext4_get_inode_loc:4358: comm kworker/u4:1: Invalid inode table block 8391460049216894068 in block_group 0
EXT4-fs error (device loop2) in ext4_reserve_inode_write:5881: Corrupt filesystem
EXT4-fs error (device loop2): ext4_dirty_inode:6085: inode #15: comm kworker/u4:1: mark_inode_dirty error
EXT4-fs (loop2): Delayed block allocation failed for inode 15 at logical offset 1 with max blocks 3 with error 117
EXT4-fs (loop2): This should not happen!! Data will be lost

EXT4-fs error (device loop2): __ext4_get_inode_loc:4358: comm kworker/u4:1: Invalid inode table block 8391460049216894068 in block_group 0
EXT4-fs error (device loop2): __ext4_get_inode_loc:4358: comm kworker/u4:1: Invalid inode table block 8391460049216894068 in block_group 0
EXT4-fs error (device loop2) in ext4_reserve_inode_write:5881: Corrupt filesystem
EXT4-fs (loop2): Delayed block allocation failed for inode 15 at logical offset 16 with max blocks 1 with error 117
EXT4-fs (loop2): This should not happen!! Data will be lost