================================================================== 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 ffff88812c3e0cf4 by task syz.5.255/1226 CPU: 0 PID: 1226 Comm: syz.5.255 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 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 _ext4_get_block+0x1ea/0x540 fs/ext4/inode.c:817 ext4_get_block+0x39/0x50 fs/ext4/inode.c:834 __block_write_begin_int+0x4de/0x14d0 fs/buffer.c:2012 __block_write_begin fs/buffer.c:2062 [inline] block_page_mkwrite+0x205/0x270 fs/buffer.c:2525 ext4_page_mkwrite+0x4c7/0x12f0 fs/ext4/inode.c:6284 do_page_mkwrite mm/memory.c:3085 [inline] wp_page_shared+0x473/0x720 mm/memory.c:3447 do_wp_page+0xaa1/0xc90 mm/memory.c:3557 handle_pte_fault+0x762/0x2710 mm/memory.c:4932 __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 RIP: 0033:0x7f218cb88807 Code: ce 48 ff c7 48 01 fe 48 8d 54 11 80 0f 1f 80 00 00 00 00 c5 fe 6f 0e c5 fe 6f 56 20 c5 fe 6f 5e 40 c5 fe 6f 66 60 48 83 ee 80 fd 7f 0f c5 fd 7f 57 20 c5 fd 7f 5f 40 c5 fd 7f 67 60 48 83 ef RSP: 002b:00007ffd4ae66e48 EFLAGS: 00010203 RAX: 0000200000002380 RBX: 0000000000000004 RCX: 0000200000002380 RDX: 0000200000002ec8 RSI: 0000001b32e3360b RDI: 00002000000023a0 RBP: fffffffffffffffe R08: 0000000000000000 R09: 000000000000002f R10: 0000000000000bc8 R11: 0000000000000001 R12: 00007ffd4ae66f70 R13: 00007f218ce32fac R14: 000000000000edfb R15: 00007f218ce32fa0 The buggy address belongs to the page: page:ffffea0004b0f800 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x12c3e0 flags: 0x4000000000000000(zone=1) raw: 4000000000000000 ffffea0004b0f848 ffffea0004cdbf48 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 1237, ts 61453045964, free_ts 61739752371 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:1587 [inline] shmem_alloc_and_acct_page+0x4a2/0x8d0 mm/shmem.c:1612 shmem_getpage_gfp+0xfe5/0x2310 mm/shmem.c:1908 shmem_getpage mm/shmem.c:152 [inline] shmem_write_begin+0xce/0x1b0 mm/shmem.c:2476 generic_perform_write+0x2b7/0x690 mm/filemap.c:3870 __generic_file_write_iter+0x268/0x480 mm/filemap.c:3998 generic_file_write_iter+0xa9/0x1d0 mm/filemap.c:4030 call_write_iter include/linux/fs.h:2212 [inline] new_sync_write fs/read_write.c:507 [inline] vfs_write+0x835/0xfd0 fs/read_write.c:594 ksys_write+0x149/0x250 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 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:965 shmem_truncate_range mm/shmem.c:1064 [inline] shmem_evict_inode+0x21a/0xa10 mm/shmem.c:1146 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 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop+0xd0/0xe0 kernel/entry/common.c:181 Memory state around the buggy address: ffff88812c3e0b80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff88812c3e0c00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >ffff88812c3e0c80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff88812c3e0d00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff88812c3e0d80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ================================================================== EXT4-fs error (device loop5): __ext4_get_inode_loc:4358: comm syz.5.255: Invalid inode table block 5510568700656870687 in block_group 0 EXT4-fs error (device loop5) in ext4_reserve_inode_write:5885: Corrupt filesystem EXT4-fs error (device loop5): ext4_dirty_inode:6089: inode #15: comm syz.5.255: mark_inode_dirty error EXT4-fs error (device loop5): __ext4_get_inode_loc:4358: comm syz.5.255: Invalid inode table block 5510568700656870687 in block_group 0 EXT4-fs error (device loop5) in ext4_reserve_inode_write:5885: Corrupt filesystem EXT4-fs error (device loop5): ext4_dirty_inode:6089: inode #15: comm syz.5.255: mark_inode_dirty error