================================================================== BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:827 [inline] BUG: KASAN: use-after-free in ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:946 Read of size 4 at addr ffff888134750018 by task syz.4.442/1927 CPU: 0 PID: 1927 Comm: syz.4.442 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 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308 ext4_ext_binsearch fs/ext4/extents.c:827 [inline] ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:946 ext4_ext_map_blocks+0x207/0x61e0 fs/ext4/extents.c:4172 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 call_write_iter include/linux/fs.h:2212 [inline] new_sync_write fs/read_write.c:507 [inline] vfs_write+0x835/0xfd0 fs/read_write.c:594 ksys_pwrite64 fs/read_write.c:701 [inline] __do_sys_pwrite64 fs/read_write.c:711 [inline] __se_sys_pwrite64 fs/read_write.c:708 [inline] __x64_sys_pwrite64+0x197/0x220 fs/read_write.c:708 x64_sys_call+0xa6/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:19 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: 0033:0x7fae02f75799 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:00007fae019d0028 EFLAGS: 00000246 ORIG_RAX: 0000000000000012 RAX: ffffffffffffffda RBX: 00007fae031eefa0 RCX: 00007fae02f75799 RDX: 00000000200000c1 RSI: 00002000000000c0 RDI: 0000000000000005 RBP: 00007fae0300bc99 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000009000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fae031ef038 R14: 00007fae031eefa0 R15: 00007fff4d48d0f8 Allocated by task 332: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track mm/kasan/common.c:45 [inline] set_alloc_info mm/kasan/common.c:433 [inline] __kasan_slab_alloc+0xbd/0xf0 mm/kasan/common.c:466 kasan_slab_alloc include/linux/kasan.h:217 [inline] slab_post_alloc_hook+0x4f/0x2b0 mm/slab.h:550 slab_alloc_node mm/slub.c:3245 [inline] slab_alloc mm/slub.c:3255 [inline] kmem_cache_alloc+0xf7/0x260 mm/slub.c:3260 getname_flags+0xb9/0x500 fs/namei.c:138 getname fs/namei.c:217 [inline] __do_sys_rename fs/namei.c:5040 [inline] __se_sys_rename fs/namei.c:5037 [inline] __x64_sys_rename+0x6e/0x90 fs/namei.c:5037 x64_sys_call+0x680/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:83 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 Freed by task 332: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track+0x4a/0x70 mm/kasan/common.c:45 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370 ____kasan_slab_free+0x125/0x160 mm/kasan/common.c:365 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:373 kasan_slab_free include/linux/kasan.h:193 [inline] slab_free_hook mm/slub.c:1728 [inline] slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1754 slab_free mm/slub.c:3526 [inline] kmem_cache_free+0x100/0x320 mm/slub.c:3544 putname fs/namei.c:271 [inline] do_renameat2+0xecf/0xfd0 fs/namei.c:5019 __do_sys_rename fs/namei.c:5039 [inline] __se_sys_rename fs/namei.c:5037 [inline] __x64_sys_rename+0x86/0x90 fs/namei.c:5037 x64_sys_call+0x680/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:83 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 The buggy address belongs to the object at ffff888134750000 which belongs to the cache names_cache of size 4096 The buggy address is located 24 bytes inside of 4096-byte region [ffff888134750000, ffff888134751000) The buggy address belongs to the page: page:ffffea0004d1d400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x134750 head:ffffea0004d1d400 order:3 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head|zone=1) raw: 4000000000010200 dead000000000100 dead000000000122 ffff8881001c4180 raw: 0000000000000000 0000000000070007 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 342, ts 50087965854, free_ts 50021777197 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_slab_page mm/slub.c:-1 [inline] allocate_slab mm/slub.c:1937 [inline] new_slab+0xa1/0x4d0 mm/slub.c:2000 ___slab_alloc+0x381/0x810 mm/slub.c:3033 __slab_alloc+0x49/0x90 mm/slub.c:3120 slab_alloc_node mm/slub.c:3211 [inline] slab_alloc mm/slub.c:3255 [inline] kmem_cache_alloc+0x138/0x260 mm/slub.c:3260 getname_flags+0xb9/0x500 fs/namei.c:138 user_path_at_empty+0x30/0x1c0 fs/namei.c:2890 user_path_at include/linux/namei.h:57 [inline] vfs_statx+0x109/0xa20 fs/stat.c:221 vfs_fstatat fs/stat.c:243 [inline] __do_sys_newfstatat fs/stat.c:411 [inline] __se_sys_newfstatat+0x10e/0x3d0 fs/stat.c:405 __x64_sys_newfstatat+0x9b/0xb0 fs/stat.c:405 x64_sys_call+0x2c1/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:263 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 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+0xae/0x540 mm/page_alloc.c:3616 free_the_page mm/page_alloc.c:805 [inline] __free_pages+0x6c/0x100 mm/page_alloc.c:5898 free_pages+0x82/0x90 mm/page_alloc.c:5909 __stack_depot_save+0x454/0x480 lib/stackdepot.c:358 kasan_save_stack mm/kasan/common.c:39 [inline] kasan_set_track+0x5b/0x70 mm/kasan/common.c:45 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370 ____kasan_slab_free+0x125/0x160 mm/kasan/common.c:365 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:373 kasan_slab_free include/linux/kasan.h:193 [inline] slab_free_hook mm/slub.c:1728 [inline] slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1754 slab_free mm/slub.c:3526 [inline] kmem_cache_free+0x100/0x320 mm/slub.c:3544 taskstats_tgid_free include/linux/taskstats_kern.h:22 [inline] free_signal_struct kernel/fork.c:777 [inline] put_signal_struct kernel/fork.c:791 [inline] __put_task_struct+0x1ba/0x3e0 kernel/fork.c:806 put_task_struct include/linux/sched/task.h:141 [inline] delayed_put_task_struct+0x6c/0x1a0 kernel/exit.c:222 rcu_do_batch+0x532/0xbe0 kernel/rcu/tree.c:2523 rcu_core+0x5ee/0xf80 kernel/rcu/tree.c:2763 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2776 Memory state around the buggy address: ffff88813474ff00: fb fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88813474ff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888134750000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888134750080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888134750100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== EXT4-fs error (device loop4): ext4_map_blocks:740: inode #15: block 145058225455267: comm syz.4.442: lblock 164 mapped to illegal pblock 145058225455267 (length 1) EXT4-fs error (device loop4): ext4_map_blocks:740: inode #15: block 145058225455222: comm syz.4.442: lblock 119 mapped to illegal pblock 145058225455222 (length 1) EXT4-fs (loop4): Delayed block allocation failed for inode 15 at logical offset 119 with max blocks 1 with error 117 EXT4-fs (loop4): This should not happen!! Data will be lost