================================================================== BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:826 [inline] BUG: KASAN: use-after-free in ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:945 Read of size 4 at addr ffff888133817018 by task syz.1.86/665 CPU: 0 PID: 665 Comm: syz.1.86 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:77 dump_stack_lvl+0x1a7/0x208 lib/dump_stack.c:118 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248 __kasan_report mm/kasan/report.c:435 [inline] kasan_report+0xe2/0x130 mm/kasan/report.c:452 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308 ext4_ext_binsearch fs/ext4/extents.c:826 [inline] ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:945 ext4_ext_map_blocks+0x20b/0x5dd0 fs/ext4/extents.c:4160 ext4_map_blocks+0x985/0x1bd0 fs/ext4/inode.c:674 mpage_map_one_extent fs/ext4/inode.c:2452 [inline] mpage_map_and_submit_extent fs/ext4/inode.c:2505 [inline] ext4_writepages+0x136a/0x2eb0 fs/ext4/inode.c:2873 do_writepages+0x128/0x280 mm/page-writeback.c:2380 __filemap_fdatawrite_range+0x2a0/0x350 mm/filemap.c:427 file_write_and_wait_range+0x8c/0x110 mm/filemap.c:766 ext4_sync_file+0x1a9/0x9f0 fs/ext4/fsync.c:151 vfs_fsync_range+0x190/0x1a0 fs/sync.c:202 generic_write_sync include/linux/fs.h:2920 [inline] ext4_buffered_write_iter+0x59b/0x640 fs/ext4/file.c:278 ext4_file_write_iter+0x53f/0x1980 fs/ext4/file.c:-1 do_iter_readv_writev+0x478/0x5f0 fs/read_write.c:-1 do_iter_write+0x189/0x630 fs/read_write.c:866 vfs_writev+0x2a9/0x530 fs/read_write.c:939 do_pwritev fs/read_write.c:1036 [inline] __do_sys_pwritev2 fs/read_write.c:1095 [inline] __se_sys_pwritev2+0x1af/0x2b0 fs/read_write.c:1086 __x64_sys_pwritev2+0xbf/0xd0 fs/read_write.c:1086 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb RIP: 0033:0x7fea2fe1b629 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:00007fea2e876028 EFLAGS: 00000246 ORIG_RAX: 0000000000000148 RAX: ffffffffffffffda RBX: 00007fea30094fa0 RCX: 00007fea2fe1b629 RDX: 0000000000000001 RSI: 0000200000000100 RDI: 0000000000000004 RBP: 00007fea2feb1b39 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000005405 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fea30095038 R14: 00007fea30094fa0 R15: 00007ffcdc99f5c8 The buggy address belongs to the page: page:ffffea0004ce05c0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x133817 flags: 0x4000000000000000() raw: 4000000000000000 ffffea0004cd8508 ffffea0004cdf408 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 0x100cca(GFP_HIGHUSER_MOVABLE), pid 601, ts 32213761312, free_ts 32346978571 set_page_owner include/linux/page_owner.h:35 [inline] post_alloc_hook mm/page_alloc.c:2456 [inline] prep_new_page+0x179/0x180 mm/page_alloc.c:2462 get_page_from_freelist+0x223b/0x23d0 mm/page_alloc.c:4254 __alloc_pages_nodemask+0x290/0x620 mm/page_alloc.c:5370 __alloc_pages include/linux/gfp.h:544 [inline] __alloc_pages_node include/linux/gfp.h:557 [inline] alloc_pages_node include/linux/gfp.h:571 [inline] alloc_pages include/linux/gfp.h:590 [inline] shmem_alloc_page+0x1fd/0x380 mm/shmem.c:1584 shmem_alloc_and_acct_page+0x3b7/0x820 mm/shmem.c:1609 shmem_getpage_gfp+0x625/0x2120 mm/shmem.c:1922 shmem_getpage mm/shmem.c:165 [inline] shmem_write_begin+0xce/0x1b0 mm/shmem.c:2501 generic_perform_write+0x2ce/0x540 mm/filemap.c:3509 __generic_file_write_iter+0x24b/0x480 mm/filemap.c:3638 generic_file_write_iter+0xa9/0x1d0 mm/filemap.c:3670 call_write_iter include/linux/fs.h:2066 [inline] new_sync_write fs/read_write.c:518 [inline] vfs_write+0x758/0xdc0 fs/read_write.c:605 ksys_write+0x149/0x250 fs/read_write.c:658 __do_sys_write fs/read_write.c:670 [inline] __se_sys_write fs/read_write.c:667 [inline] __x64_sys_write+0x7b/0x90 fs/read_write.c:667 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb page last free stack trace: reset_page_owner include/linux/page_owner.h:28 [inline] free_pages_prepare mm/page_alloc.c:1349 [inline] free_pcp_prepare mm/page_alloc.c:1421 [inline] free_unref_page_prepare+0x2b7/0x2d0 mm/page_alloc.c:3336 free_unref_page_list+0x129/0x9c0 mm/page_alloc.c:3443 release_pages+0xe52/0xea0 mm/swap.c:1103 __pagevec_release+0x71/0xe0 mm/swap.c:1123 pagevec_release include/linux/pagevec.h:88 [inline] shmem_undo_range+0x74a/0x1810 mm/shmem.c:969 shmem_truncate_range mm/shmem.c:1073 [inline] shmem_evict_inode+0x210/0xa00 mm/shmem.c:1173 evict+0x4ae/0x930 fs/inode.c:612 iput_final fs/inode.c:1736 [inline] iput+0x638/0x7c0 fs/inode.c:1762 dentry_unlink_inode+0x2cf/0x380 fs/dcache.c:378 __dentry_kill+0x44f/0x650 fs/dcache.c:583 dentry_kill+0xc0/0x2a0 fs/dcache.c:-1 dput+0x42/0x80 fs/dcache.c:883 __fput+0x4fe/0x770 fs/file_table.c:294 ____fput+0x15/0x20 fs/file_table.c:314 task_work_run+0x127/0x190 kernel/task_work.c:189 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_user_mode_loop+0xcb/0xe0 kernel/entry/common.c:172 Memory state around the buggy address: ffff888133816f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff888133816f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >ffff888133817000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff888133817080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff888133817100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ================================================================== EXT4-fs (loop1): Delayed block allocation failed for inode 15 at logical offset 188 with max blocks 4 with error 117 EXT4-fs (loop1): This should not happen!! Data will be lost