==================================================================
BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:827 [inline]
BUG: KASAN: use-after-free in ext4_find_extent+0xbab/0xdb0 fs/ext4/extents.c:946
Read of size 4 at addr ffff888125206064 by task kworker/u4:2/45

CPU: 1 PID: 45 Comm: kworker/u4:2 Not tainted 5.15.161-syzkaller-1074726-gb92c0d35d015 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Workqueue: writeback wb_workfn (flush-7:0)
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x151/0x1c0 lib/dump_stack.c:106
 print_address_description+0x87/0x3b0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:427 [inline]
 kasan_report+0x179/0x1c0 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+0xbab/0xdb0 fs/ext4/extents.c:946
 ext4_ext_map_blocks+0x269/0x74a0 fs/ext4/extents.c:4142
 ext4_map_blocks+0xaa7/0x1e00 fs/ext4/inode.c:646
 mpage_map_one_extent fs/ext4/inode.c:2409 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2462 [inline]
 ext4_writepages+0x1628/0x4000 fs/ext4/inode.c:2830
 do_writepages+0x40e/0x670 mm/page-writeback.c:2366
 __writeback_single_inode+0xdf/0xa70 fs/fs-writeback.c:1647
 writeback_sb_inodes+0xb2a/0x1920 fs/fs-writeback.c:1930
 wb_writeback+0x3b9/0x9e0 fs/fs-writeback.c:2104
 wb_do_writeback fs/fs-writeback.c:2247 [inline]
 wb_workfn+0x3d9/0x1110 fs/fs-writeback.c:2288
 process_one_work+0x6bb/0xc10 kernel/workqueue.c:2325
 worker_thread+0xad5/0x12a0 kernel/workqueue.c:2472
 kthread+0x421/0x510 kernel/kthread.c:337
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:300
 </TASK>

The buggy address belongs to the page:
page:ffffea0004948180 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x125206
flags: 0x4000000000000000(zone=1)
raw: 4000000000000000 ffffea0004948188 ffffea0004948188 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:
 ffff888125205f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888125205f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888125206000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                       ^
 ffff888125206080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888125206100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
------------[ cut here ]------------
kernel BUG at fs/ext4/inode.c:2421!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 45 Comm: kworker/u4:2 Tainted: G    B             5.15.161-syzkaller-1074726-gb92c0d35d015 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Workqueue: writeback wb_workfn (flush-7:0)
RIP: 0010:mpage_map_one_extent fs/ext4/inode.c:2421 [inline]
RIP: 0010:mpage_map_and_submit_extent fs/ext4/inode.c:2462 [inline]
RIP: 0010:ext4_writepages+0x3f4b/0x4000 fs/ext4/inode.c:2830
Code: 00 74 08 48 89 df e8 c4 cf c9 ff 48 8b 3b 48 8b 74 24 48 48 8b 54 24 28 44 89 e9 45 89 f8 e8 ac 3a 08 00 eb 58 e8 75 9c 87 ff <0f> 0b e8 6e 9c 87 ff eb 3b e8 67 9c 87 ff eb 72 e8 60 9c 87 ff 31
RSP: 0018:ffffc900002ef000 EFLAGS: 00010293
RAX: ffffffff81e8c15b RBX: dffffc0000000000 RCX: ffff8881055c4f00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900002ef410 R08: ffffffff81e89b1b R09: ffffed102125de05
R10: 0000000000000000 R11: dffffc0000000001 R12: 0000000000000000
R13: ffffc900002ef2e0 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c0012c7000 CR3: 0000000119f41000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 do_writepages+0x40e/0x670 mm/page-writeback.c:2366
 __writeback_single_inode+0xdf/0xa70 fs/fs-writeback.c:1647
 writeback_sb_inodes+0xb2a/0x1920 fs/fs-writeback.c:1930
 wb_writeback+0x3b9/0x9e0 fs/fs-writeback.c:2104
 wb_do_writeback fs/fs-writeback.c:2247 [inline]
 wb_workfn+0x3d9/0x1110 fs/fs-writeback.c:2288
 process_one_work+0x6bb/0xc10 kernel/workqueue.c:2325
 worker_thread+0xad5/0x12a0 kernel/workqueue.c:2472
 kthread+0x421/0x510 kernel/kthread.c:337
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:300
 </TASK>
Modules linked in:
---[ end trace 294465e61f2986af ]---
RIP: 0010:mpage_map_one_extent fs/ext4/inode.c:2421 [inline]
RIP: 0010:mpage_map_and_submit_extent fs/ext4/inode.c:2462 [inline]
RIP: 0010:ext4_writepages+0x3f4b/0x4000 fs/ext4/inode.c:2830
Code: 00 74 08 48 89 df e8 c4 cf c9 ff 48 8b 3b 48 8b 74 24 48 48 8b 54 24 28 44 89 e9 45 89 f8 e8 ac 3a 08 00 eb 58 e8 75 9c 87 ff <0f> 0b e8 6e 9c 87 ff eb 3b e8 67 9c 87 ff eb 72 e8 60 9c 87 ff 31
RSP: 0018:ffffc900002ef000 EFLAGS: 00010293
RAX: ffffffff81e8c15b RBX: dffffc0000000000 RCX: ffff8881055c4f00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900002ef410 R08: ffffffff81e89b1b R09: ffffed102125de05
R10: 0000000000000000 R11: dffffc0000000001 R12: 0000000000000000
R13: ffffc900002ef2e0 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c0012c7000 CR3: 000000010c903000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400