==================================================================
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 ffff888123d02a58 by task kworker/u4:2/48

CPU: 0 PID: 48 Comm: kworker/u4:2 Not tainted 5.10.238-syzkaller-1007479-gd76d4cd0623a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: ext4-rsv-conversion ext4_end_io_rsv_work
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+0x978/0x1bc0 fs/ext4/inode.c:674
 ext4_convert_unwritten_extents+0x21c/0x3f0 fs/ext4/extents.c:4860
 ext4_convert_unwritten_io_end_vec+0x103/0x180 fs/ext4/extents.c:4899
 ext4_end_io_end fs/ext4/page-io.c:189 [inline]
 ext4_do_flush_completed_IO fs/ext4/page-io.c:262 [inline]
 ext4_end_io_rsv_work+0x2b9/0x600 fs/ext4/page-io.c:276
 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:ffffea00048f4080 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x123d02
flags: 0x4000000000000000()
raw: 4000000000000000 ffffea00048f40c8 ffffea00048f4048 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 427, ts 50047162965, free_ts 50896168181
 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:5357
 __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:1584
 shmem_alloc_and_acct_page+0x36f/0x7b0 mm/shmem.c:1609
 shmem_getpage_gfp+0x625/0x2110 mm/shmem.c:1922
 shmem_getpage mm/shmem.c:165 [inline]
 shmem_write_begin+0xce/0x1b0 mm/shmem.c:2501
 generic_perform_write+0x2be/0x510 mm/filemap.c:3509
 __generic_file_write_iter+0x24b/0x480 mm/filemap.c:3638
 generic_file_write_iter+0xa9/0x1d0 mm/filemap.c:3670
 call_write_iter include/linux/fs.h:2058 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0x725/0xd60 fs/read_write.c:605
 ksys_write+0x140/0x240 fs/read_write.c:658
 __do_sys_write fs/read_write.c:670 [inline]
 __se_sys_write fs/read_write.c:667 [inline]
 __x64_sys_write+0x7b/0x90 fs/read_write.c:667
 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:969
 shmem_truncate_range mm/shmem.c:1073 [inline]
 shmem_evict_inode+0x1fd/0x9c0 mm/shmem.c:1173
 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
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_user_mode_loop+0xcb/0xe0 kernel/entry/common.c:172

Memory state around the buggy address:
 ffff888123d02900: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888123d02980: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888123d02a00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                    ^
 ffff888123d02a80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888123d02b00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
EXT4-fs error (device loop5): ext4_ext_split:1073: inode #19: comm kworker/u4:2: p_ext > EXT_MAX_EXTENT!
EXT4-fs warning (device loop5): ext4_convert_unwritten_extents:4867: inode #19: block 11: len 1: ext4_ext_map_blocks returned -117
EXT4-fs (loop5): failed to convert unwritten extents to written extents -- potential data loss!  (inode 19, error -117)
EXT4-fs warning (device loop5): ext4_convert_unwritten_extents:4867: inode #19: block 12: len 1: ext4_ext_map_blocks returned -117
EXT4-fs (loop5): failed to convert unwritten extents to written extents -- potential data loss!  (inode 19, error -117)
EXT4-fs warning (device loop5): ext4_convert_unwritten_extents:4867: inode #19: block 13: len 1: ext4_ext_map_blocks returned -117
EXT4-fs (loop5): failed to convert unwritten extents to written extents -- potential data loss!  (inode 19, error -117)
EXT4-fs warning (device loop5): ext4_convert_unwritten_extents:4867: inode #19: block 14: len 1: ext4_ext_map_blocks returned -117
EXT4-fs (loop5): failed to convert unwritten extents to written extents -- potential data loss!  (inode 19, error -117)
EXT4-fs warning (device loop5): ext4_convert_unwritten_extents:4867: inode #19: block 15: len 1: ext4_ext_map_blocks returned -117
EXT4-fs (loop5): failed to convert unwritten extents to written extents -- potential data loss!  (inode 19, error -117)
EXT4-fs error (device loop0): __ext4_get_inode_loc:4438: comm kworker/u4:2: Invalid inode table block 34360905424 in block_group 0
EXT4-fs error (device loop2): ext4_map_blocks:740: inode #19: block 198: comm kworker/u4:2: lblock 6 mapped to illegal pblock 198 (length 1)
EXT4-fs warning (device loop2): ext4_convert_unwritten_extents:4867: inode #19: block 6: len 1: ext4_ext_map_blocks returned -117
EXT4-fs error (device loop2): __ext4_get_inode_loc:4438: comm kworker/u4:2: Invalid inode table block 34360905424 in block_group 0
EXT4-fs error (device loop2) in ext4_reserve_inode_write:5932: Corrupt filesystem
EXT4-fs error (device loop2): ext4_convert_unwritten_extents:4868: inode #19: comm kworker/u4:2: mark_inode_dirty error
EXT4-fs (loop2): failed to convert unwritten extents to written extents -- potential data loss!  (inode 19, error -117)
EXT4-fs error (device loop2): ext4_find_extent:928: inode #19: comm kworker/u4:2: pblk 208 bad header/extent: invalid magic - magic 6f69, entries 29795, max 9324(0), depth 20297(0)
EXT4-fs warning (device loop2): ext4_convert_unwritten_extents:4867: inode #19: block 7: len 1: ext4_ext_map_blocks returned -117
EXT4-fs error (device loop2): __ext4_get_inode_loc:4438: comm kworker/u4:2: Invalid inode table block 34360905424 in block_group 0
EXT4-fs error (device loop2) in ext4_reserve_inode_write:5932: Corrupt filesystem
EXT4-fs error (device loop2): ext4_convert_unwritten_extents:4868: inode #19: comm kworker/u4:2: mark_inode_dirty error
EXT4-fs (loop2): failed to convert unwritten extents to written extents -- potential data loss!  (inode 19, error -117)
EXT4-fs error (device loop2): ext4_find_extent:928: inode #19: comm kworker/u4:2: pblk 208 bad header/extent: invalid magic - magic 6f69, entries 29795, max 9324(0), depth 20297(0)
EXT4-fs warning (device loop2): ext4_convert_unwritten_extents:4867: inode #19: block 8: len 1: ext4_ext_map_blocks returned -117
EXT4-fs (loop2): failed to convert unwritten extents to written extents -- potential data loss!  (inode 19, error -117)
EXT4-fs warning (device loop2): ext4_convert_unwritten_extents:4867: inode #19: block 9: len 1: ext4_ext_map_blocks returned -117
EXT4-fs (loop2): failed to convert unwritten extents to written extents -- potential data loss!  (inode 19, error -117)
EXT4-fs warning (device loop2): ext4_convert_unwritten_extents:4867: inode #19: block 10: len 1: ext4_ext_map_blocks returned -117
EXT4-fs (loop2): failed to convert unwritten extents to written extents -- potential data loss!  (inode 19, error -117)
EXT4-fs warning (device loop2): ext4_convert_unwritten_extents:4867: inode #19: block 11: len 1: ext4_ext_map_blocks returned -117
EXT4-fs (loop2): failed to convert unwritten extents to written extents -- potential data loss!  (inode 19, error -117)
EXT4-fs warning (device loop2): ext4_convert_unwritten_extents:4867: inode #19: block 12: len 1: ext4_ext_map_blocks returned -117
EXT4-fs (loop2): failed to convert unwritten extents to written extents -- potential data loss!  (inode 19, error -117)
EXT4-fs warning (device loop2): ext4_convert_unwritten_extents:4867: inode #19: block 13: len 1: ext4_ext_map_blocks returned -117
EXT4-fs (loop2): failed to convert unwritten extents to written extents -- potential data loss!  (inode 19, error -117)
EXT4-fs warning (device loop2): ext4_convert_unwritten_extents:4867: inode #19: block 14: len 1: ext4_ext_map_blocks returned -117
EXT4-fs warning (device loop2): ext4_convert_unwritten_extents:4867: inode #19: block 15: len 1: ext4_ext_map_blocks returned -117
EXT4-fs error (device loop3): __ext4_get_inode_loc:4438: comm kworker/u4:2: Invalid inode table block 34360905424 in block_group 0
EXT4-fs error (device loop5): __ext4_get_inode_loc:4438: comm kworker/u4:2: Invalid inode table block 34360905424 in block_group 0