EXT4-fs (loop8): mounted filesystem without journal. Opts: delalloc,data_err=abort,barrier=0x0000000000000003,dioread_lock,data_err=ignore,max_dir_size_kb=0x00000000004007b1,data_err=ignore,grpquota,nobh,user_xattr,bh,dioread_nolock,,errors=continue. Quota mode: writeback.
==================================================================
BUG: KASAN: slab-out-of-bounds in ext4_ext_binsearch fs/ext4/extents.c:827 [inline]
BUG: KASAN: slab-out-of-bounds in ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:946
Read of size 4 at addr ffff88810af8ce98 by task syz.8.1801/6943

CPU: 1 PID: 6943 Comm: syz.8.1801 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
 <TASK>
 __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_binsearch fs/ext4/extents.c:827 [inline]
 ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:946
 ext4_ext_map_blocks+0x1de/0x6280 fs/ext4/extents.c:4166
 ext4_map_blocks+0x3a7/0x1b20 fs/ext4/inode.c:601
 ext4_alloc_file_blocks+0x36a/0xb40 fs/ext4/extents.c:4528
 ext4_zero_range+0x449/0xd00 fs/ext4/extents.c:4645
 ext4_fallocate+0x56a/0x1de0 fs/ext4/extents.c:4780
 vfs_fallocate+0x4b4/0x590 fs/open.c:309
 ksys_fallocate fs/open.c:332 [inline]
 __do_sys_fallocate fs/open.c:340 [inline]
 __se_sys_fallocate fs/open.c:338 [inline]
 __x64_sys_fallocate+0xc0/0x110 fs/open.c:338
 x64_sys_call+0x7ec/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:286
 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: 0033:0x7f2755fb7ba9
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:00007f2754a20038 EFLAGS: 00000246 ORIG_RAX: 000000000000011d
RAX: ffffffffffffffda RBX: 00007f27561fefa0 RCX: 00007f2755fb7ba9
RDX: 0000000000000006 RSI: 0000000000000010 RDI: 0000000000000007
RBP: 00007f275603ae19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000010001 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f27561ff038 R14: 00007f27561fefa0 R15: 00007ffe60268ce8
 </TASK>

Allocated by task 1:
 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
 kmem_cache_zalloc include/linux/slab.h:737 [inline]
 __kernfs_new_node+0xdb/0x680 fs/kernfs/dir.c:593
 kernfs_new_node+0x150/0x260 fs/kernfs/dir.c:669
 __kernfs_create_file+0x4e/0x270 fs/kernfs/file.c:987
 sysfs_add_file_mode_ns+0x29a/0x350 fs/sysfs/file.c:317
 create_files fs/sysfs/group.c:64 [inline]
 internal_create_group+0x489/0xcf0 fs/sysfs/group.c:149
 internal_create_groups fs/sysfs/group.c:189 [inline]
 sysfs_create_groups+0x58/0x120 fs/sysfs/group.c:215
 device_add_groups drivers/base/core.c:2501 [inline]
 device_add_attrs+0x155/0x700 drivers/base/core.c:2660
 device_add+0x5e3/0xed0 drivers/base/core.c:3373
 netdev_register_kobject+0x179/0x320 net/core/net-sysfs.c:2014
 register_netdevice+0xdfa/0x13a0 net/core/dev.c:10405
 ifb_init_one+0x75/0xc0 drivers/net/ifb.c:315
 ifb_init_module+0x73/0x100 drivers/net/ifb.c:337
 do_one_initcall+0x17f/0x500 init/main.c:1304
 do_initcall_level+0x16f/0x2d0 init/main.c:1377
 do_initcalls+0x50/0xa0 init/main.c:1393
 do_basic_setup+0x81/0x90 init/main.c:1412
 kernel_init_freeable+0x282/0x3c0 init/main.c:1617
 kernel_init+0x1d/0x1b0 init/main.c:1508
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

The buggy address belongs to the object at ffff88810af8ce10
 which belongs to the cache kernfs_node_cache of size 136
The buggy address is located 0 bytes to the right of
 136-byte region [ffff88810af8ce10, ffff88810af8ce98)
The buggy address belongs to the page:
page:ffffea00042be300 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10af8c
flags: 0x4000000000000200(slab|zone=1)
raw: 4000000000000200 0000000000000000 dead000000000122 ffff8881001c5e00
raw: 0000000000000000 0000000000140014 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 1, ts 2671648713, free_ts 0
 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:5808
 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
 kmem_cache_zalloc include/linux/slab.h:737 [inline]
 __kernfs_new_node+0xdb/0x680 fs/kernfs/dir.c:593
 kernfs_new_node+0x150/0x260 fs/kernfs/dir.c:669
 __kernfs_create_file+0x4e/0x270 fs/kernfs/file.c:987
 sysfs_add_file_mode_ns+0x29a/0x350 fs/sysfs/file.c:317
 create_files fs/sysfs/group.c:64 [inline]
 internal_create_group+0x489/0xcf0 fs/sysfs/group.c:149
 internal_create_groups fs/sysfs/group.c:189 [inline]
 sysfs_create_groups+0x58/0x120 fs/sysfs/group.c:215
 device_add_groups drivers/base/core.c:2501 [inline]
 device_add_attrs+0x8c/0x700 drivers/base/core.c:2649
 device_add+0x5e3/0xed0 drivers/base/core.c:3373
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88810af8cd80: 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc
 ffff88810af8ce00: fc fc 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88810af8ce80: 00 00 00 fc fc fc fc fc fc fc fc 00 00 00 00 00
                            ^
 ffff88810af8cf00: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
 ffff88810af8cf80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
EXT4-fs error (device loop8): ext4_map_blocks:630: inode #15: block 2258942049: comm syz.8.1801: lblock 1 mapped to illegal pblock 2258942049 (length 64)