==================================================================
BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:840 [inline]
BUG: KASAN: use-after-free in ext4_find_extent+0x94c/0xb0c fs/ext4/extents.c:955
Read of size 4 at addr ffff0000f0700c70 by task kworker/u8:9/2160

CPU: 0 UID: 0 PID: 2160 Comm: kworker/u8:9 Not tainted 6.14.0-rc5-syzkaller-g77c95b8c7a16 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: writeback wb_workfn (flush-7:0)
Call trace:
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:466 (C)
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0x198/0x550 mm/kasan/report.c:521
 kasan_report+0xd8/0x138 mm/kasan/report.c:634
 __asan_report_load4_noabort+0x20/0x2c mm/kasan/report_generic.c:380
 ext4_ext_binsearch fs/ext4/extents.c:840 [inline]
 ext4_find_extent+0x94c/0xb0c fs/ext4/extents.c:955
 ext4_ext_map_blocks+0x2b0/0x6600 fs/ext4/extents.c:4205
 ext4_map_create_blocks fs/ext4/inode.c:516 [inline]
 ext4_map_blocks+0x710/0x15d0 fs/ext4/inode.c:702
 mpage_map_one_extent fs/ext4/inode.c:2219 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2272 [inline]
 ext4_do_writepages+0x195c/0x318c fs/ext4/inode.c:2735
 ext4_writepages+0x198/0x308 fs/ext4/inode.c:2824
 do_writepages+0x304/0x7d0 mm/page-writeback.c:2687
 __writeback_single_inode+0x15c/0x15a4 fs/fs-writeback.c:1680
 writeback_sb_inodes+0x650/0x1088 fs/fs-writeback.c:1976
 wb_writeback+0x3e0/0xe9c fs/fs-writeback.c:2156
 wb_do_writeback fs/fs-writeback.c:2303 [inline]
 wb_workfn+0x38c/0x1048 fs/fs-writeback.c:2343
 process_one_work+0x810/0x1638 kernel/workqueue.c:3238
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x97c/0xeec kernel/workqueue.c:3400
 kthread+0x65c/0x7b0 kernel/kthread.c:464
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:862

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x27 pfn:0x130700
flags: 0x5ffc00000000000(node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000000000 fffffdffc3c1c048 fffffdffc3c10fc8 0000000000000000
raw: 0000000000000027 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000f0700b00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff0000f0700b80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff0000f0700c00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                             ^
 ffff0000f0700c80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff0000f0700d00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
EXT4-fs error (device loop0): ext4_map_blocks:705: inode #19: comm kworker/u8:9: lblock 0 mapped to illegal pblock 0 (length 1)
EXT4-fs (loop0): Delayed block allocation failed for inode 19 at logical offset 0 with max blocks 1 with error 117
EXT4-fs (loop0): This should not happen!! Data will be lost

EXT4-fs error (device loop0): ext4_ext_split:1150: inode #19: comm kworker/u8:9: eh_entries 26982 != eh_max 25964!
EXT4-fs (loop0): Delayed block allocation failed for inode 19 at logical offset 0 with max blocks 1 with error 117
EXT4-fs (loop0): This should not happen!! Data will be lost

EXT4-fs error (device loop0): ext4_map_blocks:705: inode #19: comm kworker/u8:9: lblock 0 mapped to illegal pblock 0 (length 1)
EXT4-fs (loop0): Delayed block allocation failed for inode 19 at logical offset 0 with max blocks 1 with error 117
EXT4-fs (loop0): This should not happen!! Data will be lost

EXT4-fs error (device loop0): ext4_map_blocks:705: inode #19: comm kworker/u8:9: lblock 0 mapped to illegal pblock 0 (length 1)
EXT4-fs (loop0): Delayed block allocation failed for inode 19 at logical offset 0 with max blocks 1 with error 117
EXT4-fs (loop0): This should not happen!! Data will be lost

EXT4-fs error (device loop0): ext4_map_blocks:705: inode #19: block 112589081161784: comm kworker/u8:9: lblock 0 mapped to illegal pblock 112589081161784 (length 1)
EXT4-fs (loop0): Delayed block allocation failed for inode 19 at logical offset 0 with max blocks 1 with error 117
EXT4-fs (loop0): This should not happen!! Data will be lost

EXT4-fs error (device loop0): ext4_ext_split:1150: inode #19: comm kworker/u8:9: eh_entries 26982 != eh_max 25964!
EXT4-fs (loop0): Delayed block allocation failed for inode 19 at logical offset 0 with max blocks 1 with error 117
EXT4-fs (loop0): This should not happen!! Data will be lost

EXT4-fs error (device loop0): ext4_map_blocks:705: inode #19: comm kworker/u8:9: lblock 0 mapped to illegal pblock 0 (length 1)
EXT4-fs (loop0): Delayed block allocation failed for inode 19 at logical offset 0 with max blocks 1 with error 117
EXT4-fs (loop0): This should not happen!! Data will be lost