================================================================== BUG: KASAN: use-after-free in ext4_ext_insert_extent+0x2048/0x47c0 fs/ext4/extents.c:2158 Read of size 404376 at addr ffff88810ed3908c by task syz.8.160/862 CPU: 0 PID: 862 Comm: syz.8.160 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 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 check_region_inline mm/kasan/generic.c:-1 [inline] kasan_check_range+0x249/0x2a0 mm/kasan/generic.c:189 memmove+0x2d/0x70 mm/kasan/shadow.c:54 ext4_ext_insert_extent+0x2048/0x47c0 fs/ext4/extents.c:2158 ext4_ext_map_blocks+0x186c/0x61e0 fs/ext4/extents.c:4368 ext4_map_blocks+0x988/0x1b30 fs/ext4/inode.c:674 _ext4_get_block+0x1ea/0x540 fs/ext4/inode.c:817 ext4_get_block_unwritten+0x2a/0x40 fs/ext4/inode.c:848 ext4_block_write_begin+0x563/0x1160 fs/ext4/inode.c:1102 ext4_write_begin+0x65a/0x12e0 fs/ext4/ext4_jbd2.h:-1 ext4_da_write_begin+0x321/0xbf0 fs/ext4/inode.c:2988 generic_perform_write+0x2b7/0x690 mm/filemap.c:3870 ext4_buffered_write_iter+0x4ed/0x670 fs/ext4/file.c:270 ext4_file_write_iter+0x440/0x1540 fs/ext4/file.c:-1 do_iter_readv_writev+0x478/0x5f0 fs/read_write.c:-1 do_iter_write+0x1fa/0x7b0 fs/read_write.c:855 vfs_writev+0x2df/0x570 fs/read_write.c:928 do_pwritev fs/read_write.c:1025 [inline] __do_sys_pwritev2 fs/read_write.c:1084 [inline] __se_sys_pwritev2+0x1af/0x2b0 fs/read_write.c:1075 __x64_sys_pwritev2+0xbf/0xd0 fs/read_write.c:1075 x64_sys_call+0x346/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:329 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: 0033:0x7f6af7710799 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f6af614a028 EFLAGS: 00000246 ORIG_RAX: 0000000000000148 RAX: ffffffffffffffda RBX: 00007f6af798a090 RCX: 00007f6af7710799 RDX: 0000000000000001 RSI: 0000200000000100 RDI: 0000000000000007 RBP: 00007f6af77a6c99 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000005405 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f6af798a128 R14: 00007f6af798a090 R15: 00007ffc11b84b98 The buggy address belongs to the page: page:ffffea00043b4e40 refcount:8 mapcount:8 mapping:0000000000000000 index:0x55f5ff724 pfn:0x10ed39 memcg:ffff888100250000 anon flags: 0x4000000000080014(uptodate|lru|swapbacked|zone=1) raw: 4000000000080014 ffffea00043b4d48 ffffea00043b4e08 ffff88810d7810b9 raw: 000000055f5ff724 0000000000000000 0000000800000007 ffff888100250000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 0, migratetype Movable, gfp_mask 0x100dca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO), pid 140, ts 5062854217, free_ts 4842200395 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] do_anonymous_page mm/memory.c:4069 [inline] handle_pte_fault+0xebf/0x2710 mm/memory.c:4909 __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 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 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+0x17e/0x310 mm/mmu_gather.c:338 exit_mmap+0x43b/0x8b0 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+0x9f2/0x27e0 kernel/exit.c:876 do_group_exit+0x141/0x310 kernel/exit.c:1003 __do_sys_exit_group kernel/exit.c:1014 [inline] __se_sys_exit_group kernel/exit.c:1012 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1012 x64_sys_call+0x832/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:232 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 Memory state around the buggy address: ffff88810ed68f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff88810ed68f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff88810ed69000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff88810ed69080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff88810ed69100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ================================================================== EXT4-fs error (device loop8): ext4_ext_split:1074: inode #15: comm syz.8.160: p_ext > EXT_MAX_EXTENT! EXT4-fs error (device loop8): mb_free_blocks:1874: group 0, inode 15: block 321:freeing already freed block (bit 20); block bitmap corrupt. EXT4-fs (loop8): Delayed block allocation failed for inode 15 at logical offset 203 with max blocks 1 with error 117 EXT4-fs (loop8): This should not happen!! Data will be lost