EXT4-fs (loop1): mounted filesystem without journal. Quota mode: writeback. ================================================================== BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:837 [inline] BUG: KASAN: use-after-free in ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:953 Read of size 4 at addr ffff88813cd1f5bc by task syz.1.206/1140 CPU: 0 PID: 1140 Comm: syz.1.206 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Call Trace: __dump_stack+0x21/0x24 lib/dump_stack.c:88 dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106 print_address_description+0x71/0x200 mm/kasan/report.c:316 print_report+0x4a/0x60 mm/kasan/report.c:420 kasan_report+0x122/0x150 mm/kasan/report.c:524 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:350 ext4_ext_binsearch fs/ext4/extents.c:837 [inline] ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:953 ext4_ext_map_blocks+0x207/0x61d0 fs/ext4/extents.c:4166 ext4_map_blocks+0x3a5/0x1b70 fs/ext4/inode.c:606 _ext4_get_block+0x1ea/0x540 fs/ext4/inode.c:822 ext4_get_block+0x39/0x50 fs/ext4/inode.c:839 ext4_block_write_begin+0x594/0x1280 fs/ext4/inode.c:1124 ext4_write_begin+0x600/0xf90 fs/ext4/ext4_jbd2.h:-1 ext4_da_write_begin+0x3e7/0x8c0 fs/ext4/inode.c:3001 generic_perform_write+0x32d/0x740 mm/filemap.c:3903 ext4_buffered_write_iter+0x367/0x630 fs/ext4/file.c:285 ext4_file_write_iter+0x191/0x1500 fs/ext4/file.c:-1 call_write_iter include/linux/fs.h:2282 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x603/0xce0 fs/read_write.c:584 ksys_write+0x149/0x250 fs/read_write.c:637 __do_sys_write fs/read_write.c:649 [inline] __se_sys_write fs/read_write.c:646 [inline] __x64_sys_write+0x7b/0x90 fs/read_write.c:646 x64_sys_call+0x27b/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:2 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fb89759c629 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:00007fb8983f2028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007fb897815fa0 RCX: 00007fb89759c629 RDX: 00000000fffffdef RSI: 00002000000000c0 RDI: 0000000000000007 RBP: 00007fb897632b39 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fb897816038 R14: 00007fb897815fa0 R15: 00007fffb230c6a8 The buggy address belongs to the physical page: page:ffffea0004f347c0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x13cd1f flags: 0x4000000000000000(zone=1) raw: 4000000000000000 ffffea0004f34788 ffffea0004f34088 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 0x141cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP|__GFP_WRITE), pid 1140, tgid 1139 (syz.1.206), ts 59043829160, free_ts 59048249463 set_page_owner include/linux/page_owner.h:33 [inline] post_alloc_hook+0x1f5/0x210 mm/page_alloc.c:2643 prep_new_page+0x1c/0x110 mm/page_alloc.c:2650 get_page_from_freelist+0x2d12/0x2d80 mm/page_alloc.c:4554 __alloc_pages+0x1d9/0x480 mm/page_alloc.c:5868 __folio_alloc+0x12/0x40 mm/page_alloc.c:5900 __folio_alloc_node include/linux/gfp.h:245 [inline] folio_alloc include/linux/gfp.h:274 [inline] filemap_alloc_folio include/linux/pagemap.h:515 [inline] __filemap_get_folio+0x721/0x9b0 mm/filemap.c:2018 pagecache_get_page+0x2b/0x110 mm/folio-compat.c:110 grab_cache_page_write_begin+0x43/0x60 mm/folio-compat.c:122 ext4_write_begin+0x256/0xf90 fs/ext4/inode.c:1221 ext4_da_write_begin+0x3e7/0x8c0 fs/ext4/inode.c:3001 generic_perform_write+0x32d/0x740 mm/filemap.c:3903 ext4_buffered_write_iter+0x367/0x630 fs/ext4/file.c:285 ext4_file_write_iter+0x191/0x1500 fs/ext4/file.c:-1 call_write_iter include/linux/fs.h:2282 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x603/0xce0 fs/read_write.c:584 ksys_pwrite64 fs/read_write.c:699 [inline] __do_sys_pwrite64 fs/read_write.c:709 [inline] __se_sys_pwrite64 fs/read_write.c:706 [inline] __x64_sys_pwrite64+0x197/0x220 fs/read_write.c:706 x64_sys_call+0x36/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:19 page last free stack trace: reset_page_owner include/linux/page_owner.h:26 [inline] free_pages_prepare mm/page_alloc.c:1551 [inline] free_pcp_prepare mm/page_alloc.c:1625 [inline] free_unref_page_prepare+0x742/0x750 mm/page_alloc.c:3589 free_unref_page_list+0x117/0x8c0 mm/page_alloc.c:3740 release_pages+0xaf2/0xb50 mm/swap.c:1048 __pagevec_release+0x71/0xe0 mm/swap.c:1068 pagevec_release include/linux/pagevec.h:71 [inline] folio_batch_release include/linux/pagevec.h:135 [inline] truncate_inode_pages_range+0x365/0xd70 mm/truncate.c:402 truncate_inode_pages mm/truncate.c:484 [inline] truncate_pagecache+0x6c/0x90 mm/truncate.c:795 ext4_setattr+0xf9d/0x1a60 fs/ext4/inode.c:5640 notify_change+0xcc3/0xf80 fs/attr.c:499 do_truncate+0x1ac/0x240 fs/open.c:66 vfs_truncate+0x26a/0x300 fs/open.c:112 do_sys_truncate+0xf2/0x1c0 fs/open.c:135 __do_sys_truncate fs/open.c:147 [inline] __se_sys_truncate fs/open.c:145 [inline] __x64_sys_truncate+0x5b/0x70 fs/open.c:145 x64_sys_call+0x679/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:77 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 Memory state around the buggy address: ffff88813cd1f480: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff88813cd1f500: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >ffff88813cd1f580: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff88813cd1f600: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff88813cd1f680: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ==================================================================