================================================================== 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 ffff888130e37e18 by task kworker/u4:2/45 CPU: 1 PID: 45 Comm: kworker/u4:2 Tainted: G W syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Workqueue: writeback wb_workfn (flush-7:0) 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:4172 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:ffffea0004c38dc0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x130e37 flags: 0x4000000000000000(zone=1) raw: 4000000000000000 ffffea0004a979c8 ffffea0004be3f88 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 1330, ts 108528722567, free_ts 109273277332 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:5822 __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] shmem_alloc_page mm/shmem.c:1591 [inline] shmem_alloc_and_acct_page+0x4a2/0x8d0 mm/shmem.c:1616 shmem_getpage_gfp+0xfe5/0x2310 mm/shmem.c:1912 shmem_fault+0x196/0x520 mm/shmem.c:2124 __do_fault+0x264/0x2f0 mm/memory.c:4192 do_read_fault mm/memory.c:4556 [inline] do_fault mm/memory.c:4697 [inline] handle_pte_fault+0x187d/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] faultin_page mm/gup.c:976 [inline] __get_user_pages+0x80e/0x10c0 mm/gup.c:1197 populate_vma_page_range mm/gup.c:1529 [inline] __mm_populate+0x324/0x470 mm/gup.c:1638 mm_populate include/linux/mm.h:2704 [inline] vm_mmap_pgoff+0x262/0x430 mm/util.c:560 ksys_mmap_pgoff+0xf6/0x1d0 mm/mmap.c:1647 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:93 [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 x64_sys_call+0x83/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:10 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 __pagevec_release+0x71/0xe0 mm/swap.c:1035 pagevec_release include/linux/pagevec.h:81 [inline] shmem_undo_range+0x595/0x1470 mm/shmem.c:969 shmem_truncate_range mm/shmem.c:1068 [inline] shmem_evict_inode+0x21a/0xa10 mm/shmem.c:1150 evict+0x4c9/0x8d0 fs/inode.c:650 iput_final fs/inode.c:1779 [inline] iput+0x635/0x7c0 fs/inode.c:1805 dentry_unlink_inode+0x32f/0x3e0 fs/dcache.c:380 __dentry_kill+0x44f/0x650 fs/dcache.c:586 dentry_kill+0xc0/0x2a0 fs/dcache.c:-1 dput+0x47/0x90 fs/dcache.c:893 __fput+0x580/0x8b0 fs/file_table.c:319 ____fput+0x15/0x20 fs/file_table.c:339 task_work_run+0x127/0x190 kernel/task_work.c:188 exit_task_work include/linux/task_work.h:33 [inline] do_exit+0xa9e/0x27e0 kernel/exit.c:889 Memory state around the buggy address: ffff888130e37d00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff888130e37d80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >ffff888130e37e00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff888130e37e80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff888130e37f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ================================================================== EXT4-fs (loop0): Delayed block allocation failed for inode 18 at logical offset 168 with max blocks 8 with error 117 EXT4-fs (loop0): This should not happen!! Data will be lost device bridge_slave_1 left promiscuous mode bridge0: port 2(bridge_slave_1) entered disabled state device bridge_slave_0 left promiscuous mode bridge0: port 1(bridge_slave_0) entered disabled state device veth1_macvtap left promiscuous mode device veth0_vlan left promiscuous mode device bridge_slave_1 left promiscuous mode bridge0: port 2(bridge_slave_1) entered disabled state device bridge_slave_0 left promiscuous mode bridge0: port 1(bridge_slave_0) entered disabled state device veth1_macvtap left promiscuous mode device veth0_vlan left promiscuous mode