==================================================================
BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:826 [inline]
BUG: KASAN: use-after-free in ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:945
Read of size 4 at addr ffff88813243a018 by task kworker/u4:2/49

CPU: 0 PID: 49 Comm: kworker/u4:2 Not tainted 5.10.236-syzkaller-00012-gab07aeb2c93d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: writeback wb_workfn (flush-7:2)
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_binsearch fs/ext4/extents.c:826 [inline]
 ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:945
 ext4_ext_map_blocks+0x1de/0x5d40 fs/ext4/extents.c:4159
 ext4_map_blocks+0x993/0x1b80 fs/ext4/inode.c:673
 mpage_map_one_extent fs/ext4/inode.c:2451 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2504 [inline]
 ext4_writepages+0x11d5/0x2e00 fs/ext4/inode.c:2872
 do_writepages+0x12a/0x270 mm/page-writeback.c:2380
 __writeback_single_inode+0xd5/0xa20 fs/fs-writeback.c:1470
 writeback_sb_inodes+0x860/0x1400 fs/fs-writeback.c:1733
 wb_writeback+0x3e3/0xb90 fs/fs-writeback.c:1908
 wb_do_writeback fs/fs-writeback.c:2053 [inline]
 wb_workfn+0x38f/0xe20 fs/fs-writeback.c:2094
 process_one_work+0x6e1/0xba0 kernel/workqueue.c:2301
 worker_thread+0xa6a/0x13b0 kernel/workqueue.c:2447
 kthread+0x346/0x3d0 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298

The buggy address belongs to the page:
page:ffffea0004c90e80 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x13243a
flags: 0x4000000000000000()
raw: 4000000000000000 dead000000000100 dead000000000122 0000000000000000
raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x100cca(GFP_HIGHUSER_MOVABLE), pid 1001, ts 53123351427, free_ts 53975249719
 set_page_owner include/linux/page_owner.h:35 [inline]
 post_alloc_hook mm/page_alloc.c:2456 [inline]
 prep_new_page+0x179/0x180 mm/page_alloc.c:2462
 get_page_from_freelist+0x2235/0x23d0 mm/page_alloc.c:4254
 __alloc_pages_nodemask+0x268/0x5f0 mm/page_alloc.c:5349
 __alloc_pages include/linux/gfp.h:544 [inline]
 __alloc_pages_node include/linux/gfp.h:557 [inline]
 alloc_pages_node include/linux/gfp.h:571 [inline]
 alloc_pages include/linux/gfp.h:590 [inline]
 shmem_alloc_page+0x1b1/0x300 mm/shmem.c:1580
 shmem_alloc_and_acct_page+0x36f/0x7b0 mm/shmem.c:1605
 shmem_getpage_gfp+0x625/0x2110 mm/shmem.c:1918
 shmem_fault+0x2b7/0x640 mm/shmem.c:2139
 __do_fault mm/memory.c:4064 [inline]
 do_read_fault mm/memory.c:4399 [inline]
 do_fault mm/memory.c:4527 [inline]
 handle_pte_fault+0x1fa5/0x3750 mm/memory.c:4791
 __handle_mm_fault mm/memory.c:4944 [inline]
 handle_mm_fault+0xf3f/0x16a0 mm/memory.c:5358
 faultin_page mm/gup.c:902 [inline]
 __get_user_pages+0xbe9/0x13e0 mm/gup.c:1121
 populate_vma_page_range mm/gup.c:1454 [inline]
 __mm_populate+0x33b/0x420 mm/gup.c:1502
 mm_populate include/linux/mm.h:2782 [inline]
 vm_mmap_pgoff+0x223/0x340 mm/util.c:548
 ksys_mmap_pgoff+0xfd/0x1e0 mm/mmap.c:1700
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:95 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:86 [inline]
 __x64_sys_mmap+0xfa/0x110 arch/x86/kernel/sys_x86_64.c:86
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:28 [inline]
 free_pages_prepare mm/page_alloc.c:1349 [inline]
 free_pcp_prepare mm/page_alloc.c:1421 [inline]
 free_unref_page_prepare+0x2b7/0x2d0 mm/page_alloc.c:3336
 free_unref_page_list+0x12e/0x9b0 mm/page_alloc.c:3443
 release_pages+0xe38/0xe80 mm/swap.c:1103
 __pagevec_release+0x71/0xe0 mm/swap.c:1123
 pagevec_release include/linux/pagevec.h:88 [inline]
 shmem_undo_range+0x6e1/0x1760 mm/shmem.c:965
 shmem_truncate_range mm/shmem.c:1069 [inline]
 shmem_evict_inode+0x1fd/0x9c0 mm/shmem.c:1169
 evict+0x478/0x910 fs/inode.c:612
 iput_final fs/inode.c:1736 [inline]
 iput+0x638/0x7c0 fs/inode.c:1762
 dentry_unlink_inode+0x2cf/0x380 fs/dcache.c:378
 __dentry_kill+0x44f/0x650 fs/dcache.c:583
 dentry_kill+0xc0/0x2a0 fs/dcache.c:-1
 dput+0x42/0x80 fs/dcache.c:883
 __fput+0x4fe/0x770 fs/file_table.c:294
 ____fput+0x15/0x20 fs/file_table.c:314
 task_work_run+0x127/0x190 kernel/task_work.c:189
 exit_task_work include/linux/task_work.h:33 [inline]
 do_exit+0xa27/0x2470 kernel/exit.c:863

Memory state around the buggy address:
 ffff888132439f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888132439f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88813243a000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                            ^
 ffff88813243a080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88813243a100: 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:2463!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 49 Comm: kworker/u4:2 Tainted: G    B             5.10.236-syzkaller-00012-gab07aeb2c93d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: writeback wb_workfn (flush-7:2)
RIP: 0010:mpage_map_one_extent fs/ext4/inode.c:2463 [inline]
RIP: 0010:mpage_map_and_submit_extent fs/ext4/inode.c:2504 [inline]
RIP: 0010:ext4_writepages+0x2d49/0x2e00 fs/ext4/inode.c:2872
Code: 08 48 89 df e8 c8 2a ce ff 48 8b 3b 48 8b 74 24 40 48 8b 54 24 28 48 8b 4c 24 20 45 89 f0 e8 de 41 07 00 eb 56 e8 07 44 94 ff <0f> 0b e8 00 44 94 ff eb 2f e8 f9 43 94 ff eb 64 e8 f2 43 94 ff 31
RSP: 0018:ffffc900009e7180 EFLAGS: 00010293
RAX: ffffffff81cf48a9 RBX: 0000000000000000 RCX: ffff8881015a62c0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900009e74f0 R08: dffffc0000000000 R09: ffffed102383d3d5
R10: ffffed102383d3d5 R11: 1ffff1102383d3d4 R12: dffffc0000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 000000000000042b
FS:  0000000000000000(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb1c2475d58 CR3: 000000010ea1f000 CR4: 00000000003526b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 do_writepages+0x12a/0x270 mm/page-writeback.c:2380
 __writeback_single_inode+0xd5/0xa20 fs/fs-writeback.c:1470
 writeback_sb_inodes+0x860/0x1400 fs/fs-writeback.c:1733
 wb_writeback+0x3e3/0xb90 fs/fs-writeback.c:1908
 wb_do_writeback fs/fs-writeback.c:2053 [inline]
 wb_workfn+0x38f/0xe20 fs/fs-writeback.c:2094
 process_one_work+0x6e1/0xba0 kernel/workqueue.c:2301
 worker_thread+0xa6a/0x13b0 kernel/workqueue.c:2447
 kthread+0x346/0x3d0 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
Modules linked in:
---[ end trace 56cbdfeeb2e97358 ]---
RIP: 0010:mpage_map_one_extent fs/ext4/inode.c:2463 [inline]
RIP: 0010:mpage_map_and_submit_extent fs/ext4/inode.c:2504 [inline]
RIP: 0010:ext4_writepages+0x2d49/0x2e00 fs/ext4/inode.c:2872
Code: 08 48 89 df e8 c8 2a ce ff 48 8b 3b 48 8b 74 24 40 48 8b 54 24 28 48 8b 4c 24 20 45 89 f0 e8 de 41 07 00 eb 56 e8 07 44 94 ff <0f> 0b e8 00 44 94 ff eb 2f e8 f9 43 94 ff eb 64 e8 f2 43 94 ff 31
RSP: 0018:ffffc900009e7180 EFLAGS: 00010293
RAX: ffffffff81cf48a9 RBX: 0000000000000000 RCX: ffff8881015a62c0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900009e74f0 R08: dffffc0000000000 R09: ffffed102383d3d5
R10: ffffed102383d3d5 R11: 1ffff1102383d3d4 R12: dffffc0000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 000000000000042b
FS:  0000000000000000(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2cd1cff8 CR3: 000000010d1bf000 CR4: 00000000003526b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400