==================================================================
BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:840 [inline]
BUG: KASAN: use-after-free in ext4_find_extent+0x8dc/0xa8c fs/ext4/extents.c:955
Read of size 4 at addr ffff0000f5769748 by task kworker/u8:6/225

CPU: 0 UID: 0 PID: 225 Comm: kworker/u8:6 Not tainted 6.15.0-rc2-syzkaller-gc72692105976 #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: ext4-rsv-conversion ext4_end_io_rsv_work
Call trace:
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:466 (C)
 __dump_stack+0x30/0x40 lib/dump_stack.c:94
 dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120
 print_address_description+0xa8/0x254 mm/kasan/report.c:408
 print_report+0x68/0x84 mm/kasan/report.c:521
 kasan_report+0xb0/0x110 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+0x8dc/0xa8c fs/ext4/extents.c:955
 ext4_ext_map_blocks+0x258/0x52ec fs/ext4/extents.c:4205
 ext4_map_create_blocks fs/ext4/inode.c:520 [inline]
 ext4_map_blocks+0x6a8/0x13ac fs/ext4/inode.c:706
 ext4_convert_unwritten_extents+0x240/0x4fc fs/ext4/extents.c:4822
 ext4_convert_unwritten_io_end_vec+0xf0/0x170 fs/ext4/extents.c:4861
 ext4_end_io_end+0xb4/0x334 fs/ext4/page-io.c:199
 ext4_do_flush_completed_IO fs/ext4/page-io.c:287 [inline]
 ext4_end_io_rsv_work+0x208/0x2cc fs/ext4/page-io.c:302
 process_one_work+0x7e8/0x156c kernel/workqueue.c:3238
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x958/0xed8 kernel/workqueue.c:3400
 kthread+0x5fc/0x75c 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:0x7b pfn:0x135769
flags: 0x5ffc00000000000(node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000000000 fffffdffc3dfb7c8 fffffdffc3d1f5c8 0000000000000000
raw: 000000000000007b 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000f5769600: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff0000f5769680: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff0000f5769700: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                              ^
 ffff0000f5769780: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff0000f5769800: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
EXT4-fs error (device loop4): ext4_map_blocks:709: inode #15: block 16777220: comm kworker/u8:6: lblock 4 mapped to illegal pblock 16777220 (length 12)
EXT4-fs warning (device loop4): ext4_convert_unwritten_extents:4829: inode #15: block 4: len 12: ext4_ext_map_blocks returned -117
EXT4-fs (loop4): failed to convert unwritten extents to written extents -- potential data loss!  (inode 15, error -117)
EXT4-fs error (device loop4): ext4_map_blocks:709: inode #15: block 209706073194608: comm kworker/u8:6: lblock 112 mapped to illegal pblock 209706073194608 (length 1)
EXT4-fs (loop4): Delayed block allocation failed for inode 15 at logical offset 112 with max blocks 1 with error 117
EXT4-fs (loop4): This should not happen!! Data will be lost

GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog