================================================================== BUG: KASAN: use-after-free in ext4_ext_insert_extent+0x3e5d/0x47a0 fs/ext4/extents.c:2076 Read of size 4 at addr ffff8881281347f4 by task syz.2.18/544 CPU: 1 PID: 544 Comm: syz.2.18 Not tainted 5.15.185-syzkaller-1080761-g5cf73bface18 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 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_insert_extent+0x3e5d/0x47a0 fs/ext4/extents.c:2076 ext4_ext_map_blocks+0x1574/0x6270 fs/ext4/extents.c:4360 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:3869 ext4_buffered_write_iter+0x4ed/0x670 fs/ext4/file.c:270 ext4_file_write_iter+0x18c/0x14c0 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: 0033:0x7fe835877929 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:00007fe8352c7038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007fe835a9f080 RCX: 00007fe835877929 RDX: 00000000002a979d RSI: 0000200000000000 RDI: 0000000000000004 RBP: 00007fe8358f9b39 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007fe835a9f080 R15: 00007ffe8a8497c8 The buggy address belongs to the page: page:ffffea0004a04d00 refcount:1 mapcount:1 mapping:0000000000000000 index:0x200000294 pfn:0x128134 memcg:ffff88810a9a2280 anon flags: 0x4000000000080014(uptodate|lru|swapbacked|zone=1) raw: 4000000000080014 ffffea0004a04cc8 ffffea0004a04d48 ffff88812a5f8da9 raw: 0000000200000294 0000000000000000 0000000100000000 ffff88810a9a2280 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 530, ts 55236731474, free_ts 29180503456 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:5795 __alloc_pages_node include/linux/gfp.h:591 [inline] alloc_pages_node include/linux/gfp.h:605 [inline] alloc_pages include/linux/gfp.h:618 [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:1836 [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 unmap_region+0x315/0x360 mm/mmap.c:2680 __do_munmap+0xa0e/0xfe0 mm/mmap.c:2913 __vm_munmap+0x15b/0x2a0 mm/mmap.c:2966 __do_sys_munmap mm/mmap.c:2992 [inline] __se_sys_munmap mm/mmap.c:2988 [inline] __x64_sys_munmap+0x6b/0x80 mm/mmap.c:2988 x64_sys_call+0xc9/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:12 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: ffff888128134680: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888128134700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff888128134780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ^ ffff888128134800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888128134880: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ================================================================== EXT4-fs error (device loop2): ext4_ext_split:1146: inode #17: comm syz.2.18: eh_entries 62719 != eh_max 50191! EXT4-fs error (device loop2): ext4_free_blocks:6223: comm syz.2.18: Freeing blocks not in datazone - block = 43314383766818, count = 8977 EXT4-fs error (device loop2): ext4_free_blocks:6223: comm syz.2.18: Freeing blocks not in datazone - block = 13299223413763, count = 24629 EXT4-fs error (device loop2): ext4_free_blocks:6223: comm syz.2.18: Freeing blocks not in datazone - block = 44555775906350, count = 9404 EXT4-fs error (device loop2): ext4_free_blocks:6223: comm syz.2.18: Freeing blocks not in datazone - block = 266233160729108, count = 25278 EXT4-fs error (device loop2): ext4_free_blocks:6223: comm syz.2.18: Freeing blocks not in datazone - block = 63289554304116, count = 14570 EXT4-fs error (device loop2): ext4_free_blocks:6223: comm syz.2.18: Freeing blocks not in datazone - block = 195964506980996, count = 27155 EXT4-fs error (device loop2): ext4_free_blocks:6223: comm syz.2.18: Freeing blocks not in datazone - block = 172853225740986, count = 9218 EXT4-fs error (device loop2): ext4_free_blocks:6223: comm syz.2.18: Freeing blocks not in datazone - block = 254502105032999, count = 22634 EXT4-fs error (device loop2): ext4_free_blocks:6223: comm syz.2.18: Freeing blocks not in datazone - block = 124058318872634, count = 20734