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BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:827 [inline]
BUG: KASAN: use-after-free in ext4_find_extent+0xbcc/0xe00 fs/ext4/extents.c:946
Read of size 4 at addr ffff88806faa1064 by task kworker/u4:2/154

CPU: 0 PID: 154 Comm: kworker/u4:2 Not tainted 5.15.181-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
Workqueue: writeback wb_workfn (flush-7:0)
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 print_address_description+0x60/0x2d0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0xdf/0x130 mm/kasan/report.c:451
 ext4_ext_binsearch fs/ext4/extents.c:827 [inline]
 ext4_find_extent+0xbcc/0xe00 fs/ext4/extents.c:946
 ext4_ext_map_blocks+0x25a/0x64e0 fs/ext4/extents.c:4165
 ext4_map_blocks+0x981/0x1b30 fs/ext4/inode.c:673
 mpage_map_one_extent fs/ext4/inode.c:2408 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2461 [inline]
 ext4_writepages+0x12ca/0x2d20 fs/ext4/inode.c:2829
 do_writepages+0x48d/0x6d0 mm/page-writeback.c:2386
 __writeback_single_inode+0x153/0xda0 fs/fs-writeback.c:1647
 writeback_sb_inodes+0x9fe/0x1610 fs/fs-writeback.c:1930
 wb_writeback+0x443/0xb90 fs/fs-writeback.c:2104
 wb_do_writeback fs/fs-writeback.c:2247 [inline]
 wb_workfn+0x423/0xe60 fs/fs-writeback.c:2288
 process_one_work+0x863/0x1000 kernel/workqueue.c:2310
 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

The buggy address belongs to the page:
page:ffffea0001bea840 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x6faa1
memcg:ffff888016a7c000
anon flags: 0xfff00000080014(uptodate|lru|swapbacked|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000080014 ffffea0001c2e088 ffffea0001be3c48 ffff8880788b3331
raw: 000000055a0e6de4 0000000000000000 0000000100000000 ffff888016a7c000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x1100cca(GFP_HIGHUSER_MOVABLE), pid 4615, ts 88074663903, free_ts 88111439473
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x1b77/0x1c60 mm/page_alloc.c:4192
 __alloc_pages+0x1e1/0x470 mm/page_alloc.c:5466
 alloc_pages_vma+0x393/0x7c0 mm/mempolicy.c:2146
 do_cow_fault mm/memory.c:4283 [inline]
 do_fault mm/memory.c:4394 [inline]
 handle_pte_fault mm/memory.c:4650 [inline]
 __handle_mm_fault mm/memory.c:4785 [inline]
 handle_mm_fault+0x1b98/0x43c0 mm/memory.c:4883
 do_user_addr_fault+0x489/0xc80 arch/x86/mm/fault.c:1357
 handle_page_fault arch/x86/mm/fault.c:1445 [inline]
 exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1501
 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:606
 __clear_user arch/x86/lib/usercopy_64.c:24 [inline]
 clear_user+0xf0/0x150 arch/x86/lib/usercopy_64.c:54
 padzero fs/binfmt_elf.c:141 [inline]
 load_elf_interp+0xc55/0xdf0 fs/binfmt_elf.c:689
 load_elf_binary+0x1caa/0x2890 fs/binfmt_elf.c:1227
 search_binary_handler fs/exec.c:1742 [inline]
 exec_binprm fs/exec.c:1783 [inline]
 bprm_execve+0xa92/0x17d0 fs/exec.c:1852
 do_execveat_common+0x51e/0x6d0 fs/exec.c:1957
 do_execve fs/exec.c:2027 [inline]
 __do_sys_execve fs/exec.c:2103 [inline]
 __se_sys_execve fs/exec.c:2098 [inline]
 __x64_sys_execve+0x8e/0xa0 fs/exec.c:2098
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1340 [inline]
 free_pcp_prepare mm/page_alloc.c:1391 [inline]
 free_unref_page_prepare+0x637/0x6c0 mm/page_alloc.c:3317
 free_unref_page_list+0x122/0x7e0 mm/page_alloc.c:3433
 release_pages+0x184b/0x1bb0 mm/swap.c:963
 tlb_batch_pages_flush mm/mmu_gather.c:49 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:240 [inline]
 tlb_flush_mmu mm/mmu_gather.c:247 [inline]
 tlb_finish_mmu+0x164/0x2e0 mm/mmu_gather.c:338
 exit_mmap+0x3a6/0x5f0 mm/mmap.c:3206
 __mmput+0x115/0x3b0 kernel/fork.c:1127
 exit_mm+0x567/0x6c0 kernel/exit.c:550
 do_exit+0x599/0x20a0 kernel/exit.c:861
 do_group_exit+0x12e/0x300 kernel/exit.c:996
 __do_sys_exit_group kernel/exit.c:1007 [inline]
 __se_sys_exit_group kernel/exit.c:1005 [inline]
 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1005
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

Memory state around the buggy address:
 ffff88806faa0f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88806faa0f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88806faa1000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                                                       ^
 ffff88806faa1080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88806faa1100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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