================================================================== BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:837 [inline] BUG: KASAN: use-after-free in ext4_find_extent+0xbc8/0xde0 fs/ext4/extents.c:953 Read of size 4 at addr ffff888037f17e2c by task syz-executor.1/9575 CPU: 1 PID: 9575 Comm: syz-executor.1 Not tainted 6.3.0-syzkaller-13027-g1a5304fecee5 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:351 [inline] print_report+0x163/0x540 mm/kasan/report.c:462 kasan_report+0x176/0x1b0 mm/kasan/report.c:572 ext4_ext_binsearch fs/ext4/extents.c:837 [inline] ext4_find_extent+0xbc8/0xde0 fs/ext4/extents.c:953 ext4_ext_map_blocks+0x2d1/0x7210 fs/ext4/extents.c:4102 ext4_map_blocks+0xa4c/0x1cf0 fs/ext4/inode.c:623 _ext4_get_block+0x238/0x6a0 fs/ext4/inode.c:779 __block_write_begin_int+0x548/0x1a50 fs/buffer.c:2064 __block_write_begin fs/buffer.c:2114 [inline] block_page_mkwrite+0x2fc/0x620 fs/buffer.c:2588 ext4_page_mkwrite+0x4ff/0x1290 fs/ext4/inode.c:6116 do_page_mkwrite+0x1a4/0x600 mm/memory.c:2931 wp_page_shared mm/memory.c:3280 [inline] do_wp_page+0x501/0x3690 mm/memory.c:3362 handle_pte_fault mm/memory.c:4964 [inline] __handle_mm_fault mm/memory.c:5089 [inline] handle_mm_fault+0x2371/0x5860 mm/memory.c:5243 do_user_addr_fault arch/x86/mm/fault.c:1440 [inline] handle_page_fault arch/x86/mm/fault.c:1534 [inline] exc_page_fault+0x7d2/0x910 arch/x86/mm/fault.c:1590 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570 RIP: 0010:rep_movs_alternative+0x5f/0xb0 arch/x86/lib/copy_user_64.S:74 Code: 07 48 83 c6 08 48 83 c7 08 83 e9 08 74 df 83 f9 08 73 e8 eb c9 66 0f 1f 44 00 00 4c 8b 06 4c 8b 4e 08 4c 8b 56 10 4c 8b 5e 18 <4c> 89 07 4c 89 4f 08 4c 89 57 10 4c 89 5f 18 4c 8b 46 20 4c 8b 4e RSP: 0018:ffffc90004a6f898 EFLAGS: 00050202 RAX: ffffffff84310901 RBX: 0000000000000f60 RCX: 0000000000000a20 RDX: 0000000000000000 RSI: ffff88802fb3d540 RDI: 0000000020002000 RBP: ffffc90004a6f9f8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 1ffff9200094dfb3 R13: 0000000020001ac0 R14: ffff88802fb3d000 R15: 00007fffffffe0a0 copy_user_generic arch/x86/include/asm/uaccess_64.h:31 [inline] raw_copy_to_user arch/x86/include/asm/uaccess_64.h:52 [inline] copyout lib/iov_iter.c:170 [inline] _copy_to_iter+0x2fe/0x1100 lib/iov_iter.c:535 copy_page_to_iter+0xe7/0x1d0 lib/iov_iter.c:733 copy_folio_to_iter include/linux/uio.h:196 [inline] filemap_read+0x8e5/0x1170 mm/filemap.c:2742 blkdev_read_iter+0x3e5/0x530 block/fops.c:606 call_read_iter include/linux/fs.h:1862 [inline] new_sync_read fs/read_write.c:389 [inline] vfs_read+0x7b1/0xb80 fs/read_write.c:470 ksys_read+0x1a0/0x2c0 fs/read_write.c:613 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f05b968c169 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f05ba4ae168 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 00007f05b97abf80 RCX: 00007f05b968c169 RDX: 0000000000002020 RSI: 0000000020000a00 RDI: 0000000000000005 RBP: 00007f05b96e7ca1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffd7d1fe79f R14: 00007f05ba4ae300 R15: 0000000000022000 The buggy address belongs to the physical page: page:ffffea0000dfc5c0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x37f17 flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff) page_type: 0xffffffff() raw: 00fff00000000000 ffffea0000e27e88 ffffea0000e1ebc8 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 9453, tgid 9449 (syz-executor.4), ts 361083677515, free_ts 362868189978 set_page_owner include/linux/page_owner.h:31 [inline] post_alloc_hook+0x1e6/0x210 mm/page_alloc.c:1722 prep_new_page mm/page_alloc.c:1729 [inline] get_page_from_freelist+0x321c/0x33a0 mm/page_alloc.c:3493 __alloc_pages+0x255/0x670 mm/page_alloc.c:4759 __folio_alloc+0x13/0x30 mm/page_alloc.c:4791 vma_alloc_folio+0x48a/0x9a0 mm/mempolicy.c:2238 shmem_alloc_folio mm/shmem.c:1579 [inline] shmem_alloc_and_acct_folio+0x5e7/0xe10 mm/shmem.c:1603 shmem_get_folio_gfp+0x120f/0x3470 mm/shmem.c:1948 shmem_get_folio mm/shmem.c:2079 [inline] shmem_write_begin+0x172/0x4e0 mm/shmem.c:2573 generic_perform_write+0x300/0x5e0 mm/filemap.c:3923 __generic_file_write_iter+0x17a/0x400 mm/filemap.c:4051 generic_file_write_iter+0xaf/0x310 mm/filemap.c:4083 call_write_iter include/linux/fs.h:1868 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x7ec/0xc10 fs/read_write.c:584 ksys_write+0x1a0/0x2c0 fs/read_write.c:637 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1302 [inline] free_unref_page_prepare+0x903/0xa30 mm/page_alloc.c:2555 free_unref_page_list+0x596/0x830 mm/page_alloc.c:2696 release_pages+0x2193/0x2470 mm/swap.c:1042 __pagevec_release+0x84/0x100 mm/swap.c:1062 pagevec_release include/linux/pagevec.h:63 [inline] folio_batch_release include/linux/pagevec.h:132 [inline] shmem_undo_range+0x6af/0x1ba0 mm/shmem.c:954 shmem_truncate_range mm/shmem.c:1049 [inline] shmem_evict_inode+0x258/0x9f0 mm/shmem.c:1164 evict+0x2a4/0x620 fs/inode.c:665 __dentry_kill+0x436/0x650 fs/dcache.c:607 dentry_kill+0xbb/0x290 dput+0x1f3/0x420 fs/dcache.c:913 __fput+0x5e4/0x890 fs/file_table.c:329 task_work_run+0x24a/0x300 kernel/task_work.c:179 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop+0xd9/0x100 kernel/entry/common.c:171 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:204 __syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline] syscall_exit_to_user_mode+0x64/0x280 kernel/entry/common.c:297 do_syscall_64+0x4d/0xc0 arch/x86/entry/common.c:86 Memory state around the buggy address: ffff888037f17d00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff888037f17d80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >ffff888037f17e00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff888037f17e80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff888037f17f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ================================================================== ---------------- Code disassembly (best guess), 1 bytes skipped: 0: 48 83 c6 08 add $0x8,%rsi 4: 48 83 c7 08 add $0x8,%rdi 8: 83 e9 08 sub $0x8,%ecx b: 74 df je 0xffffffec d: 83 f9 08 cmp $0x8,%ecx 10: 73 e8 jae 0xfffffffa 12: eb c9 jmp 0xffffffdd 14: 66 0f 1f 44 00 00 nopw 0x0(%rax,%rax,1) 1a: 4c 8b 06 mov (%rsi),%r8 1d: 4c 8b 4e 08 mov 0x8(%rsi),%r9 21: 4c 8b 56 10 mov 0x10(%rsi),%r10 25: 4c 8b 5e 18 mov 0x18(%rsi),%r11 * 29: 4c 89 07 mov %r8,(%rdi) <-- trapping instruction 2c: 4c 89 4f 08 mov %r9,0x8(%rdi) 30: 4c 89 57 10 mov %r10,0x10(%rdi) 34: 4c 89 5f 18 mov %r11,0x18(%rdi) 38: 4c 8b 46 20 mov 0x20(%rsi),%r8 3c: 4c rex.WR 3d: 8b .byte 0x8b 3e: 4e rex.WRX