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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 ffff88813322e018 by task kworker/u4:5/702

CPU: 0 PID: 702 Comm: kworker/u4:5 Not tainted 5.10.240-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: writeback wb_workfn (flush-7:7)
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:4160
 ext4_map_blocks+0x978/0x1bc0 fs/ext4/inode.c:674
 mpage_map_one_extent fs/ext4/inode.c:2452 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2505 [inline]
 ext4_writepages+0x11d5/0x2e00 fs/ext4/inode.c:2873
 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:ffffea0004cc8b80 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x13322e
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 6386, ts 250662510380, free_ts 250799283488
 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_fault+0x2b7/0x640 mm/shmem.c:2143
 __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:1708
 __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: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
 exit_task_work include/linux/task_work.h:33 [inline]
 do_exit+0xa4f/0x2480 kernel/exit.c:872

Memory state around the buggy address:
 ffff88813322df00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88813322df80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88813322e000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                            ^
 ffff88813322e080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88813322e100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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