================================================================== 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 ffff8881239cdeb8 by task kworker/u4:1/10 CPU: 0 PID: 10 Comm: kworker/u4:1 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Workqueue: writeback wb_workfn (flush-7:5) 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:ffffea00048e7340 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x1239cd flags: 0x4000000000000000(zone=1) raw: 4000000000000000 ffffea00048e7388 ffffea00048e7308 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 0x100dca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO), pid 395, ts 43701058096, free_ts 43745394413 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_anonymous_page mm/memory.c:4069 [inline] handle_pte_fault+0xebf/0x2710 mm/memory.c:4909 __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:1418 handle_page_fault arch/x86/mm/fault.c:1509 [inline] exc_page_fault+0x51/0xb0 arch/x86/mm/fault.c:1565 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:1014 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 unmap_region+0x344/0x3b0 mm/mmap.c:2692 __do_munmap+0xa24/0x1020 mm/mmap.c:2925 __vm_munmap+0x163/0x2b0 mm/mmap.c:2978 __do_sys_munmap mm/mmap.c:3004 [inline] __se_sys_munmap mm/mmap.c:3000 [inline] __x64_sys_munmap+0x6b/0x80 mm/mmap.c:3000 x64_sys_call+0xc9/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:12 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: ffff8881239cdd80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff8881239cde00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >ffff8881239cde80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff8881239cdf00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff8881239cdf80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ================================================================== EXT4-fs error (device loop5): ext4_ext_split:1146: inode #18: comm kworker/u4:1: eh_entries 29811 != eh_max 28005! EXT4-fs error (device loop5): mb_free_blocks:1860: group 0, inode 18: block 305:freeing already freed block (bit 19); block bitmap corrupt. EXT4-fs (loop5): Delayed block allocation failed for inode 18 at logical offset 168 with max blocks 8 with error 117 EXT4-fs (loop5): This should not happen!! Data will be lost EXT4-fs (loop5): Delayed block allocation failed for inode 18 at logical offset 168 with max blocks 8 with error 117 EXT4-fs (loop5): This should not happen!! Data will be lost EXT4-fs error (device loop6): ext4_ext_split:1146: inode #18: comm kworker/u4:1: eh_entries 29811 != eh_max 28005! EXT4-fs error (device loop6): mb_free_blocks:1860: group 0, inode 18: block 305:freeing already freed block (bit 19); block bitmap corrupt. EXT4-fs (loop6): Delayed block allocation failed for inode 18 at logical offset 168 with max blocks 8 with error 117 EXT4-fs (loop6): This should not happen!! Data will be lost EXT4-fs error (device loop1): ext4_map_blocks:740: inode #18: block 1653562406320: comm kworker/u4:1: lblock 168 mapped to illegal pblock 1653562406320 (length 8) EXT4-fs (loop1): Delayed block allocation failed for inode 18 at logical offset 168 with max blocks 8 with error 117 EXT4-fs (loop1): This should not happen!! Data will be lost