================================================================== 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 ffff8881284eea44 by task syz.0.16/540 CPU: 1 PID: 540 Comm: syz.0.16 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 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+0x1db/0x6270 fs/ext4/extents.c:4166 ext4_map_blocks+0x97b/0x1b20 fs/ext4/inode.c:674 _ext4_get_block+0x1da/0x4e0 fs/ext4/inode.c:817 ext4_get_block+0x39/0x50 fs/ext4/inode.c:834 ext4_block_write_begin+0x556/0x1150 fs/ext4/inode.c:1102 ext4_write_begin+0x638/0x1220 fs/ext4/ext4_jbd2.h:-1 ext4_da_write_begin+0x2fa/0xb60 fs/ext4/inode.c:2988 generic_perform_write+0x2ad/0x670 mm/filemap.c:3870 ext4_buffered_write_iter+0x4ed/0x670 fs/ext4/file.c:270 ext4_file_write_iter+0x18c/0x1550 fs/ext4/file.c:664 call_write_iter include/linux/fs.h:2212 [inline] new_sync_write fs/read_write.c:507 [inline] vfs_write+0x802/0xf70 fs/read_write.c:594 ksys_write+0x140/0x240 fs/read_write.c:647 __do_sys_write fs/read_write.c:659 [inline] __se_sys_write fs/read_write.c:656 [inline] __x64_sys_write+0x7b/0x90 fs/read_write.c:656 x64_sys_call+0x8ef/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:2 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 RIP: 0033:0x7eff6b6af929 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007eff6b0ff038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007eff6b8d7080 RCX: 00007eff6b6af929 RDX: 00000000002a979d RSI: 0000200000000000 RDI: 0000000000000004 RBP: 00007eff6b731b39 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007eff6b8d7080 R15: 00007ffecde96468 The buggy address belongs to the page: page:ffffea0004a13b80 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x1284ee flags: 0x4000000000000000(zone=1) raw: 4000000000000000 ffffea0004a13bc8 ffffea0004a13b48 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 521, ts 49693848550, free_ts 50357908987 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] do_anonymous_page mm/memory.c:4069 [inline] handle_pte_fault+0xe89/0x2680 mm/memory.c:4909 __handle_mm_fault mm/memory.c:-1 [inline] do_handle_mm_fault+0x1a6d/0x1d50 mm/memory.c:5333 handle_mm_fault include/linux/mm.h:1847 [inline] do_user_addr_fault+0x841/0x1180 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+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: ffff8881284ee900: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff8881284ee980: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >ffff8881284eea00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff8881284eea80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff8881284eeb00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ================================================================== EXT4-fs error (device loop0): ext4_map_blocks:740: inode #17: block 219257987891890: comm syz.0.16: lblock 148 mapped to illegal pblock 219257987891890 (length 1)