EXT4-fs (loop7): mounted filesystem without journal. Opts: delalloc,bsdgroups,inode_readahead_blks=0x0000000000000100,nodioread_nolock,bh,max_dir_size_kb=0x00000000004007b1,data_err=ignore,nouid32,quota,user_xattr,nouid32,dioread_nolock,,errors=continue
==================================================================
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 ffff88811af1f018 by task syz.7.198/1087

CPU: 1 PID: 1087 Comm: syz.7.198 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:4166
 ext4_map_blocks+0x985/0x1bd0 fs/ext4/inode.c:674
 _ext4_get_block+0x1d1/0x4e0 fs/ext4/inode.c:817
 ext4_get_block_unwritten+0x2a/0x40 fs/ext4/inode.c:848
 ext4_block_write_begin+0x573/0x1340 fs/ext4/inode.c:1101
 ext4_write_begin+0x67e/0x1690 fs/ext4/ext4_jbd2.h:-1
 ext4_da_write_begin+0x478/0xf10 fs/ext4/inode.c:3033
 generic_perform_write+0x2ce/0x540 mm/filemap.c:3509
 ext4_buffered_write_iter+0x4b8/0x640 fs/ext4/file.c:271
 ext4_file_write_iter+0x53f/0x1980 fs/ext4/file.c:-1
 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_pwrite64 fs/read_write.c:712 [inline]
 __do_sys_pwrite64 fs/read_write.c:722 [inline]
 __se_sys_pwrite64 fs/read_write.c:719 [inline]
 __x64_sys_pwrite64+0x197/0x220 fs/read_write.c:719
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f188f811799
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:00007f188e26c028 EFLAGS: 00000246 ORIG_RAX: 0000000000000012
RAX: ffffffffffffffda RBX: 00007f188fa8afa0 RCX: 00007f188f811799
RDX: 00000000200000c1 RSI: 00002000000000c0 RDI: 0000000000000005
RBP: 00007f188f8a7c99 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000009000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f188fa8b038 R14: 00007f188fa8afa0 R15: 00007fff482f7928

Allocated by task 317:
 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:430 [inline]
 __kasan_slab_alloc+0xbd/0xf0 mm/kasan/common.c:463
 kasan_slab_alloc include/linux/kasan.h:244 [inline]
 slab_post_alloc_hook+0x5d/0x2f0 mm/slab.h:580
 slab_alloc_node mm/slub.c:2952 [inline]
 slab_alloc mm/slub.c:2960 [inline]
 kmem_cache_alloc+0x162/0x2d0 mm/slub.c:2965
 getname_flags+0xb9/0x500 fs/namei.c:141
 user_path_at_empty+0x2f/0x50 fs/namei.c:2748
 user_path_at include/linux/namei.h:60 [inline]
 vfs_statx+0x10a/0x530 fs/stat.c:193
 vfs_fstatat fs/stat.c:215 [inline]
 __do_sys_newfstatat fs/stat.c:383 [inline]
 __se_sys_newfstatat+0x10e/0x3d0 fs/stat.c:377
 __x64_sys_newfstatat+0x9b/0xb0 fs/stat.c:377
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Freed by task 317:
 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:362
 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:370
 kasan_slab_free include/linux/kasan.h:220 [inline]
 slab_free_hook mm/slub.c:1600 [inline]
 slab_free_freelist_hook+0xc5/0x190 mm/slub.c:1626
 slab_free mm/slub.c:3208 [inline]
 kmem_cache_free+0x100/0x2d0 mm/slub.c:3224
 putname fs/namei.c:262 [inline]
 filename_lookup+0x4b3/0x6a0 fs/namei.c:2478
 user_path_at_empty+0x43/0x50 fs/namei.c:2748
 user_path_at include/linux/namei.h:60 [inline]
 vfs_statx+0x10a/0x530 fs/stat.c:193
 vfs_fstatat fs/stat.c:215 [inline]
 __do_sys_newfstatat fs/stat.c:383 [inline]
 __se_sys_newfstatat+0x10e/0x3d0 fs/stat.c:377
 __x64_sys_newfstatat+0x9b/0xb0 fs/stat.c:377
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

The buggy address belongs to the object at ffff88811af1e600
 which belongs to the cache names_cache of size 4096
The buggy address is located 2584 bytes inside of
 4096-byte region [ffff88811af1e600, ffff88811af1f600)
The buggy address belongs to the page:
page:ffffea00046bc600 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11af18
head:ffffea00046bc600 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head)
raw: 4000000000010200 dead000000000100 dead000000000122 ffff88810018ac00
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 317, ts 45305928871, free_ts 45289003244
 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:5384
 alloc_slab_page mm/slub.c:-1 [inline]
 allocate_slab mm/slub.c:1813 [inline]
 new_slab+0x84/0x3f0 mm/slub.c:1874
 new_slab_objects mm/slub.c:2632 [inline]
 ___slab_alloc+0x2a6/0x450 mm/slub.c:2796
 __slab_alloc+0x63/0xa0 mm/slub.c:2836
 slab_alloc_node mm/slub.c:2918 [inline]
 slab_alloc mm/slub.c:2960 [inline]
 kmem_cache_alloc+0x1ac/0x2d0 mm/slub.c:2965
 getname_flags+0xb9/0x500 fs/namei.c:141
 user_path_at_empty+0x2f/0x50 fs/namei.c:2748
 user_path_at include/linux/namei.h:60 [inline]
 vfs_statx+0x10a/0x530 fs/stat.c:193
 vfs_fstatat fs/stat.c:215 [inline]
 __do_sys_newfstatat fs/stat.c:383 [inline]
 __se_sys_newfstatat+0x10e/0x3d0 fs/stat.c:377
 __x64_sys_newfstatat+0x9b/0xb0 fs/stat.c:377
 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_pages_ok+0x80b/0x830 mm/page_alloc.c:1629
 free_the_page mm/page_alloc.c:5445 [inline]
 __free_pages+0xd8/0x3b0 mm/page_alloc.c:5454
 __free_slab+0xcf/0x190 mm/slub.c:1899
 free_slab mm/slub.c:1914 [inline]
 discard_slab mm/slub.c:1920 [inline]
 unfreeze_partials+0x15f/0x190 mm/slub.c:2415
 put_cpu_partial+0xc1/0x180 mm/slub.c:2451
 __slab_free+0x2c9/0x3a0 mm/slub.c:3100
 do_slab_free mm/slub.c:3196 [inline]
 ___cache_free+0x10e/0x130 mm/slub.c:3215
 qlink_free+0x50/0x90 mm/kasan/quarantine.c:157
 qlist_free_all+0x5f/0xb0 mm/kasan/quarantine.c:176
 kasan_quarantine_reduce+0x14a/0x160 mm/kasan/quarantine.c:283
 __kasan_slab_alloc+0x2f/0xf0 mm/kasan/common.c:440
 kasan_slab_alloc include/linux/kasan.h:244 [inline]
 slab_post_alloc_hook+0x5d/0x2f0 mm/slab.h:580
 slab_alloc_node mm/slub.c:2952 [inline]
 slab_alloc mm/slub.c:2960 [inline]
 kmem_cache_alloc+0x162/0x2d0 mm/slub.c:2965
 getname_flags+0xb9/0x500 fs/namei.c:141
 getname fs/namei.c:212 [inline]
 __do_sys_unlinkat fs/namei.c:-1 [inline]
 __se_sys_unlinkat fs/namei.c:4078 [inline]
 __x64_sys_unlinkat+0xb0/0xf0 fs/namei.c:4078
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46

Memory state around the buggy address:
 ffff88811af1ef00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88811af1ef80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88811af1f000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff88811af1f080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88811af1f100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
EXT4-fs error (device loop7): ext4_ext_split:1073: inode #15: comm syz.7.198: p_ext > EXT_MAX_EXTENT!
EXT4-fs (loop7): pa ffff88812fc8e3f0: logic 128, phys. 385, len 8
EXT4-fs error (device loop7): ext4_mb_release_inode_pa:4375: group 0, free 3, pa_free 2
EXT4-fs error (device loop7): ext4_free_blocks:5701: comm syz.7.198: Freeing blocks not in datazone - block = 281472864468944, count = 16
EXT4-fs error (device loop7): ext4_free_blocks:5701: comm syz.7.198: Freeing blocks not in datazone - block = 281472864436181, count = 32767
EXT4-fs error (device loop7): ext4_free_blocks:5701: comm syz.7.198: Freeing blocks not in datazone - block = 281472864587280, count = 16
EXT4-fs error (device loop7): ext4_free_blocks:5701: comm syz.7.198: Freeing blocks not in datazone - block = 281472864554522, count = 32767
EXT4-fs error (device loop7): ext4_free_blocks:5701: comm syz.7.198: Freeing blocks not in datazone - block = 281472864447696, count = 16
EXT4-fs error (device loop7): ext4_free_blocks:5701: comm syz.7.198: Freeing blocks not in datazone - block = 281472864414939, count = 32767
EXT4-fs error (device loop7): ext4_free_blocks:5701: comm syz.7.198: Freeing blocks not in datazone - block = 281472864601392, count = 16
EXT4-fs error (device loop7): ext4_free_blocks:5701: comm syz.7.198: Freeing blocks not in datazone - block = 281472864568629, count = 32767
EXT4-fs (loop7): Delayed block allocation failed for inode 15 at logical offset 119 with max blocks 1 with error 117
EXT4-fs (loop7): This should not happen!! Data will be lost