================================================================== 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 ffff88810e93ee18 by task kworker/u4:40/4074 CPU: 0 PID: 4074 Comm: kworker/u4:40 Tainted: G W syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 Workqueue: writeback wb_workfn (flush-7:4) Call Trace: __dump_stack+0x21/0x30 lib/dump_stack.c:88 dump_stack_lvl+0xee/0x150 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+0x1de/0x6280 fs/ext4/extents.c:4166 ext4_map_blocks+0x97b/0x1b20 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+0x11e7/0x2f90 fs/ext4/inode.c:2842 do_writepages+0x48a/0x6c0 mm/page-writeback.c:2388 __writeback_single_inode+0xd5/0x9c0 fs/fs-writeback.c:1647 writeback_sb_inodes+0x9c0/0x1590 fs/fs-writeback.c:1930 wb_writeback+0x3f1/0x980 fs/fs-writeback.c:2106 wb_do_writeback fs/fs-writeback.c:2253 [inline] wb_workfn+0x38f/0xe20 fs/fs-writeback.c:2294 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:ffffea00043a4f80 refcount:0 mapcount:0 mapping:0000000000000000 index:0x100 pfn:0x10e93e flags: 0x4000000000000000(zone=1) raw: 4000000000000000 dead000000000100 dead000000000122 0000000000000000 raw: 0000000000000100 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 9075, ts 493591300677, free_ts 494094448990 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+0x2cc5/0x2d50 mm/page_alloc.c:4485 __alloc_pages+0x18f/0x440 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] wp_page_copy+0x20f/0x18f0 mm/memory.c:3226 do_wp_page+0x731/0xc90 mm/memory.c:-1 handle_pte_fault+0x73c/0x2680 mm/memory.c:4932 __handle_mm_fault mm/memory.c:-1 [inline] do_handle_mm_fault+0x1a6d/0x1d50 mm/memory.c:5333 do_user_addr_fault+0x554/0x1180 arch/x86/mm/fault.c:1325 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+0x134/0x9d0 mm/page_alloc.c:3671 release_pages+0xfda/0x1030 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+0x175/0x300 mm/mmu_gather.c:338 exit_mmap+0x40f/0x860 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+0x9d2/0x27a0 kernel/exit.c:876 do_group_exit+0x141/0x310 kernel/exit.c:1003 get_signal+0x66a/0x1480 kernel/signal.c:2907 arch_do_signal_or_restart+0xc1/0x10f0 arch/x86/kernel/signal.c:867 handle_signal_work kernel/entry/common.c:154 [inline] exit_to_user_mode_loop+0xa7/0xe0 kernel/entry/common.c:178 exit_to_user_mode_prepare+0x87/0xd0 kernel/entry/common.c:214 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline] syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:307 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86 Memory state around the buggy address: ffff88810e93ed00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff88810e93ed80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >ffff88810e93ee00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff88810e93ee80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff88810e93ef00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ================================================================== EXT4-fs error (device loop4): ext4_map_blocks:740: inode #18: block 142614389063847: comm kworker/u4:40: lblock 168 mapped to illegal pblock 142614389063847 (length 8) EXT4-fs (loop4): Delayed block allocation failed for inode 18 at logical offset 168 with max blocks 8 with error 117 EXT4-fs (loop4): This should not happen!! Data will be lost