================================================================== BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:827 [inline] BUG: KASAN: use-after-free in ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:946 Read of size 4 at addr ffff888129cd5ec4 by task kworker/u4:4/354 CPU: 0 PID: 354 Comm: kworker/u4:4 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Workqueue: writeback wb_workfn (flush-7:9) Call Trace: __dump_stack+0x21/0x30 lib/dump_stack.c:88 dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248 __kasan_report mm/kasan/report.c:427 [inline] kasan_report+0xf1/0x140 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+0xbeb/0xe20 fs/ext4/extents.c:946 ext4_ext_map_blocks+0x207/0x61e0 fs/ext4/extents.c:4166 ext4_map_blocks+0x988/0x1b30 fs/ext4/inode.c:674 mpage_map_one_extent fs/ext4/inode.c:2421 [inline] mpage_map_and_submit_extent fs/ext4/inode.c:2474 [inline] ext4_writepages+0x123f/0x3090 fs/ext4/inode.c:2842 do_writepages+0x473/0x6c0 mm/page-writeback.c:2388 __writeback_single_inode+0xd5/0x9c0 fs/fs-writeback.c:1657 writeback_sb_inodes+0xa10/0x1610 fs/fs-writeback.c:1940 wb_writeback+0x40b/0x9d0 fs/fs-writeback.c:2116 wb_do_writeback fs/fs-writeback.c:2263 [inline] wb_workfn+0x3ac/0xf30 fs/fs-writeback.c:2304 process_one_work+0x6be/0xba0 kernel/workqueue.c:2325 worker_thread+0xa59/0x1200 kernel/workqueue.c:2472 kthread+0x411/0x500 kernel/kthread.c:337 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 The buggy address belongs to the page: page:ffffea0004a73540 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x129cd5 flags: 0x4000000000000000(zone=1) raw: 4000000000000000 ffffea0004a73588 ffffea0004a73f08 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 366, ts 27704674394, free_ts 31113214181 set_page_owner include/linux/page_owner.h:33 [inline] post_alloc_hook+0x192/0x1b0 mm/page_alloc.c:2605 prep_new_page+0x1c/0x110 mm/page_alloc.c:2611 get_page_from_freelist+0x2d3a/0x2dc0 mm/page_alloc.c:4485 __alloc_pages+0x1a2/0x460 mm/page_alloc.c:5808 __alloc_pages_node include/linux/gfp.h:595 [inline] alloc_pages_node include/linux/gfp.h:609 [inline] alloc_pages include/linux/gfp.h:622 [inline] do_cow_fault mm/memory.c:4581 [inline] do_fault mm/memory.c:4699 [inline] handle_pte_fault+0x9b0/0x2710 mm/memory.c:4911 __handle_mm_fault mm/memory.c:-1 [inline] do_handle_mm_fault+0x1af9/0x1de0 mm/memory.c:5333 handle_mm_fault include/linux/mm.h:1847 [inline] do_user_addr_fault+0x828/0x1250 arch/x86/mm/fault.c:1416 handle_page_fault arch/x86/mm/fault.c:1507 [inline] exc_page_fault+0x51/0xb0 arch/x86/mm/fault.c:1560 asm_exc_page_fault+0x27/0x30 arch/x86/include/asm/idtentry.h:606 page last free stack trace: reset_page_owner include/linux/page_owner.h:26 [inline] free_pages_prepare mm/page_alloc.c:1472 [inline] free_pcp_prepare mm/page_alloc.c:1544 [inline] free_unref_page_prepare+0x542/0x550 mm/page_alloc.c:3534 free_unref_page_list+0x13a/0x9d0 mm/page_alloc.c:3671 release_pages+0x1006/0x1060 mm/swap.c:1015 free_pages_and_swap_cache+0x86/0xa0 mm/swap_state.c:320 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+0x17e/0x310 mm/mmu_gather.c:338 exit_mmap+0x43b/0x8b0 mm/mmap.c:3248 __mmput+0x93/0x320 kernel/fork.c:1180 mmput+0x50/0x150 kernel/fork.c:1203 exit_mm kernel/exit.c:554 [inline] do_exit+0x9f2/0x27e0 kernel/exit.c:876 do_group_exit+0x141/0x310 kernel/exit.c:1003 __do_sys_exit_group kernel/exit.c:1014 [inline] __se_sys_exit_group kernel/exit.c:1012 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1012 x64_sys_call+0x832/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:232 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: ffff888129cd5d80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff888129cd5e00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >ffff888129cd5e80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff888129cd5f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff888129cd5f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ================================================================== EXT4-fs error (device loop9): __ext4_get_inode_loc:4358: comm kworker/u4:4: Invalid inode table block 8391460049216894068 in block_group 0 EXT4-fs error (device loop9): __ext4_get_inode_loc:4358: comm kworker/u4:4: Invalid inode table block 8391460049216894068 in block_group 0 EXT4-fs error (device loop3): __ext4_get_inode_loc:4358: comm kworker/u4:4: Invalid inode table block 8391460049216894068 in block_group 0 EXT4-fs error (device loop3): __ext4_get_inode_loc:4358: comm kworker/u4:4: Invalid inode table block 8391460049216894068 in block_group 0 EXT4-fs error (device loop1): ext4_map_blocks:740: inode #15: block 55808805013633: comm kworker/u4:4: lblock 0 mapped to illegal pblock 55808805013633 (length 1) EXT4-fs (loop1): Delayed block allocation failed for inode 15 at logical offset 0 with max blocks 1 with error 117 EXT4-fs (loop1): This should not happen!! Data will be lost EXT4-fs error (device loop1): __ext4_get_inode_loc:4358: comm kworker/u4:4: Invalid inode table block 8391460049216894068 in block_group 0 EXT4-fs error (device loop1): __ext4_get_inode_loc:4358: comm kworker/u4:4: Invalid inode table block 8391460049216894068 in block_group 0 EXT4-fs error (device loop1): ext4_map_blocks:740: inode #15: block 55808805013669: comm kworker/u4:4: lblock 36 mapped to illegal pblock 55808805013669 (length 1) EXT4-fs (loop1): Delayed block allocation failed for inode 15 at logical offset 36 with max blocks 1 with error 117 EXT4-fs (loop1): This should not happen!! Data will be lost EXT4-fs error (device loop8): __ext4_get_inode_loc:4358: comm kworker/u4:4: Invalid inode table block 8391460049216894068 in block_group 0 EXT4-fs error (device loop8): __ext4_get_inode_loc:4358: comm kworker/u4:4: Invalid inode table block 8391460049216894068 in block_group 0