================================================================== BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:837 [inline] BUG: KASAN: use-after-free in ext4_find_extent+0xbcc/0xe00 fs/ext4/extents.c:953 Read of size 4 at addr ffff8880533fae18 by task syz.1.306/5477 CPU: 1 PID: 5477 Comm: syz.1.306 Not tainted 6.1.148-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 Call Trace: dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106 print_address_description mm/kasan/report.c:316 [inline] print_report+0xa8/0x210 mm/kasan/report.c:420 kasan_report+0x10b/0x140 mm/kasan/report.c:524 ext4_ext_binsearch fs/ext4/extents.c:837 [inline] ext4_find_extent+0xbcc/0xe00 fs/ext4/extents.c:953 ext4_ext_map_blocks+0x27d/0x66d0 fs/ext4/extents.c:4166 ext4_map_blocks+0x9d1/0x1b60 fs/ext4/inode.c:679 _ext4_get_block+0x1d7/0x4e0 fs/ext4/inode.c:822 __block_write_begin_int+0x54b/0x1a70 fs/buffer.c:1991 __block_write_begin fs/buffer.c:2041 [inline] block_page_mkwrite+0x2d8/0x5f0 fs/buffer.c:2510 ext4_page_mkwrite+0x3b2/0x10c0 fs/ext4/inode.c:6314 do_page_mkwrite+0x16b/0x5c0 mm/memory.c:3011 wp_page_shared+0x167/0x370 mm/memory.c:3360 handle_pte_fault mm/memory.c:5049 [inline] __handle_mm_fault mm/memory.c:5173 [inline] handle_mm_fault+0x1ca6/0x3e70 mm/memory.c:5294 do_user_addr_fault+0x51f/0xb10 arch/x86/mm/fault.c:1340 handle_page_fault arch/x86/mm/fault.c:1431 [inline] exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1487 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:608 RIP: 0010:copy_user_enhanced_fast_string+0xa/0x40 arch/x86/lib/copy_user_64.S:166 Code: ff c9 75 f2 89 d1 c1 e9 03 83 e2 07 f3 48 a5 89 d1 f3 a4 31 c0 0f 01 ca c3 8d 0c ca 89 ca eb 20 0f 01 cb 83 fa 40 72 38 89 d1 a4 31 c0 0f 01 ca c3 89 ca eb 0a 90 90 90 90 90 90 90 90 90 90 RSP: 0018:ffffc90003627c38 EFLAGS: 00050202 RAX: ffffffff84068701 RBX: 0000000000000841 RCX: 0000000000000781 RDX: 0000000000000841 RSI: ffff88807a6700c0 RDI: 0000200000001000 RBP: 0000000000000000 R08: dffffc0000000000 R09: ffffed100f4ce109 R10: 0000000000000000 R11: 0000000000000108 R12: 00007fffffffe7bf R13: 1ffff920006c4fa4 R14: 0000200000000f40 R15: ffff88807a670000 copy_user_generic arch/x86/include/asm/uaccess_64.h:37 [inline] raw_copy_to_user arch/x86/include/asm/uaccess_64.h:58 [inline] _copy_to_user+0xea/0x130 lib/usercopy.c:41 copy_to_user include/linux/uaccess.h:169 [inline] do_getxattr+0x336/0x370 fs/xattr.c:704 getxattr fs/xattr.c:735 [inline] path_getxattr+0x24f/0x400 fs/xattr.c:751 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fc02658ebe9 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:00007fc027496038 EFLAGS: 00000246 ORIG_RAX: 00000000000000c0 RAX: ffffffffffffffda RBX: 00007fc0267b5fa0 RCX: 00007fc02658ebe9 RDX: 0000200000000f40 RSI: 0000200000000280 RDI: 0000200000000240 RBP: 00007fc026611e19 R08: 0000000000000000 R09: 0000000000000000 R10: 00000000ffffff92 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fc0267b6038 R14: 00007fc0267b5fa0 R15: 00007ffc4ca33878 The buggy address belongs to the physical page: page:ffffea00014cfe80 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x533fa flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000000000 ffffea00014cfec8 ffffea0001401548 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 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 5438, tgid 5436 (syz.0.295), ts 190260955777, free_ts 195135546353 set_page_owner include/linux/page_owner.h:31 [inline] post_alloc_hook+0x173/0x1a0 mm/page_alloc.c:2532 prep_new_page mm/page_alloc.c:2539 [inline] get_page_from_freelist+0x1a26/0x1ac0 mm/page_alloc.c:4328 __alloc_pages+0x1df/0x4e0 mm/page_alloc.c:5614 __folio_alloc+0xe/0x30 mm/page_alloc.c:5646 vma_alloc_folio+0x4a3/0x900 mm/mempolicy.c:2243 shmem_alloc_folio mm/shmem.c:1589 [inline] shmem_alloc_and_acct_folio+0x42e/0xb60 mm/shmem.c:1613 shmem_get_folio_gfp+0x1361/0x3400 mm/shmem.c:1941 shmem_fault+0x1be/0x7b0 mm/shmem.c:2156 __do_fault+0x13b/0x4e0 mm/memory.c:4280 do_read_fault mm/memory.c:4631 [inline] do_fault mm/memory.c:4760 [inline] handle_pte_fault mm/memory.c:5031 [inline] __handle_mm_fault mm/memory.c:5173 [inline] handle_mm_fault+0x28ca/0x3e70 mm/memory.c:5294 faultin_page mm/gup.c:1026 [inline] __get_user_pages+0x3ff/0xeb0 mm/gup.c:1250 populate_vma_page_range+0x214/0x2b0 mm/gup.c:1607 __mm_populate+0x248/0x370 mm/gup.c:1721 mm_populate include/linux/mm.h:2826 [inline] vm_mmap_pgoff+0x203/0x2b0 mm/util.c:525 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1459 [inline] free_pcp_prepare mm/page_alloc.c:1509 [inline] free_unref_page_prepare+0x8b4/0x9a0 mm/page_alloc.c:3384 free_unref_page_list+0xbb/0x8e0 mm/page_alloc.c:3525 release_pages+0x1f92/0x2200 mm/swap.c:1035 __pagevec_release+0x6d/0xe0 mm/swap.c:1055 pagevec_release include/linux/pagevec.h:71 [inline] folio_batch_release include/linux/pagevec.h:135 [inline] shmem_undo_range+0x75b/0x2050 mm/shmem.c:946 shmem_truncate_range mm/shmem.c:1062 [inline] shmem_evict_inode+0x248/0xa40 mm/shmem.c:1171 evict+0x485/0x870 fs/inode.c:705 __dentry_kill+0x431/0x650 fs/dcache.c:611 dentry_kill+0xb8/0x290 fs/dcache.c:-1 dput+0xfa/0x1d0 fs/dcache.c:918 __fput+0x5e0/0x920 fs/file_table.c:328 task_work_run+0x1ca/0x250 kernel/task_work.c:203 exit_task_work include/linux/task_work.h:39 [inline] do_exit+0x93e/0x2400 kernel/exit.c:880 do_group_exit+0x217/0x2d0 kernel/exit.c:1022 get_signal+0x1272/0x1350 kernel/signal.c:2871 arch_do_signal_or_restart+0xb0/0x1230 arch/x86/kernel/signal.c:871 Memory state around the buggy address: ffff8880533fad00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff8880533fad80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >ffff8880533fae00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff8880533fae80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff8880533faf00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ================================================================== ---------------- Code disassembly (best guess): 0: ff c9 dec %ecx 2: 75 f2 jne 0xfffffff6 4: 89 d1 mov %edx,%ecx 6: c1 e9 03 shr $0x3,%ecx 9: 83 e2 07 and $0x7,%edx c: f3 48 a5 rep movsq %ds:(%rsi),%es:(%rdi) f: 89 d1 mov %edx,%ecx 11: f3 a4 rep movsb %ds:(%rsi),%es:(%rdi) 13: 31 c0 xor %eax,%eax 15: 0f 01 ca clac 18: c3 ret 19: 8d 0c ca lea (%rdx,%rcx,8),%ecx 1c: 89 ca mov %ecx,%edx 1e: eb 20 jmp 0x40 20: 0f 01 cb stac 23: 83 fa 40 cmp $0x40,%edx 26: 72 38 jb 0x60 28: 89 d1 mov %edx,%ecx * 2a: f3 a4 rep movsb %ds:(%rsi),%es:(%rdi) <-- trapping instruction 2c: 31 c0 xor %eax,%eax 2e: 0f 01 ca clac 31: c3 ret 32: 89 ca mov %ecx,%edx 34: eb 0a jmp 0x40 36: 90 nop 37: 90 nop 38: 90 nop 39: 90 nop 3a: 90 nop 3b: 90 nop 3c: 90 nop 3d: 90 nop 3e: 90 nop 3f: 90 nop