KASAN: slab-out-of-bounds Read in count_subheaders

Status: auto-obsoleted due to no activity on 2025/08/30 05:38
Reported-by: syzbot+f8cff86565e569940389@syzkaller.appspotmail.com
First crash: 448d, last: 448d
▶ ▼ Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream BUG: unable to handle kernel paging request in count_subheaders fs 8 1 1369d 1369d 0/29 auto-obsoleted due to no activity on 2023/02/13 16:10

Sample crash report:
==================================================================
BUG: KASAN: slab-out-of-bounds in count_subheaders+0x69/0xf0 fs/proc/proc_sysctl.c:1445
Read of size 8 at addr ffff888028c9a3b8 by task syz.3.556/6397

CPU: 0 PID: 6397 Comm: syz.3.556 Not tainted 5.15.183-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 print_address_description+0x60/0x2d0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0xdf/0x130 mm/kasan/report.c:451
 count_subheaders+0x69/0xf0 fs/proc/proc_sysctl.c:1445
 unregister_sysctl_table+0x5b/0x130 fs/proc/proc_sysctl.c:1702
 ax25_unregister_dev_sysctl+0x79/0xa0 net/ax25/sysctl_net_ax25.c:178
 ax25_dev_device_down+0x5b/0x520 net/ax25/ax25_dev.c:101
 ax25_device_event+0x4b4/0x4f0 net/ax25/af_ax25.c:144
 notifier_call_chain kernel/notifier.c:83 [inline]
 raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:391
 call_netdevice_notifiers_extack net/core/dev.c:2061 [inline]
 call_netdevice_notifiers net/core/dev.c:2075 [inline]
 dev_close_many+0x28d/0x400 net/core/dev.c:1650
 dev_close+0x14c/0x200 net/core/dev.c:1672
 bpq_device_event+0x2f4/0x9c0 drivers/net/hamradio/bpqether.c:548
 notifier_call_chain kernel/notifier.c:83 [inline]
 raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:391
 call_netdevice_notifiers_extack net/core/dev.c:2061 [inline]
 call_netdevice_notifiers net/core/dev.c:2075 [inline]
 dev_close_many+0x28d/0x400 net/core/dev.c:1650
 dev_close+0x14c/0x200 net/core/dev.c:1672
 bond_setup_by_slave+0x61/0x3a0 drivers/net/bonding/bond_main.c:1471
 bond_enslave+0x77c/0x3a40 drivers/net/bonding/bond_main.c:1855
 bond_do_ioctl+0x2a2/0x8c0 drivers/net/bonding/bond_main.c:4238
 dev_ifsioc+0xc01/0xe70 net/core/dev_ioctl.c:417
 dev_ioctl+0x55f/0xe50 net/core/dev_ioctl.c:587
 sock_do_ioctl+0x222/0x2f0 net/socket.c:1154
 sock_ioctl+0x4ed/0x6e0 net/socket.c:1257
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
 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: 0033:0x7f9cceb50969
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:00007f9ccc997038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f9cced78080 RCX: 00007f9cceb50969
RDX: 0000200000000180 RSI: 0000000000008990 RDI: 0000000000000008
RBP: 00007f9ccebd2ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f9cced78080 R15: 00007fff95200448
 </TASK>

Allocated by task 4168:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 ____kasan_kmalloc mm/kasan/common.c:513 [inline]
 __kasan_kmalloc+0xb5/0xf0 mm/kasan/common.c:522
 kmalloc include/linux/slab.h:604 [inline]
 kzalloc include/linux/slab.h:735 [inline]
 obj_cgroup_alloc mm/memcontrol.c:314 [inline]
 memcg_online_kmem mm/memcontrol.c:3662 [inline]
 mem_cgroup_css_alloc+0x10fe/0x1640 mm/memcontrol.c:5312
 css_create kernel/cgroup/cgroup.c:5365 [inline]
 cgroup_apply_control_enable+0x3cc/0xb00 kernel/cgroup/cgroup.c:3189
 cgroup_mkdir+0xcdf/0xf00 kernel/cgroup/cgroup.c:5585
 kernfs_iop_mkdir+0x24c/0x3d0 fs/kernfs/dir.c:1175
 vfs_mkdir+0x387/0x570 fs/namei.c:4065
 do_mkdirat+0x1d7/0x5a0 fs/namei.c:4090
 __do_sys_mkdirat fs/namei.c:4105 [inline]
 __se_sys_mkdirat fs/namei.c:4103 [inline]
 __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4103
 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 ffff888028c9a380
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 56 bytes inside of
 64-byte region [ffff888028c9a380, ffff888028c9a3c0)
The buggy address belongs to the page:
page:ffffea0000a32680 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x28c9a
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffffea0000885100 0000000500000005 ffff888016841640
raw: 0000000000000000 0000000000200020 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 9, ts 10791052001, free_ts 10788711873
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x1b77/0x1c60 mm/page_alloc.c:4192
 __alloc_pages+0x1e1/0x470 mm/page_alloc.c:5466
 alloc_slab_page mm/slub.c:1775 [inline]
 allocate_slab mm/slub.c:1912 [inline]
 new_slab+0xc0/0x4b0 mm/slub.c:1975
 ___slab_alloc+0x81e/0xdf0 mm/slub.c:3008
 __slab_alloc mm/slub.c:3095 [inline]
 slab_alloc_node mm/slub.c:3186 [inline]
 slab_alloc mm/slub.c:3228 [inline]
 __kmalloc+0x1cd/0x330 mm/slub.c:4403
 kmalloc include/linux/slab.h:609 [inline]
 kzalloc include/linux/slab.h:735 [inline]
 lsm_task_alloc security/security.c:616 [inline]
 security_task_alloc+0x42/0x130 security/security.c:1677
 copy_process+0x1639/0x3e60 kernel/fork.c:2187
 kernel_clone+0x219/0x930 kernel/fork.c:2603
 kernel_thread+0xc8/0x120 kernel/fork.c:2655
 call_usermodehelper_exec_work+0x58/0x220 kernel/umh.c:174
 process_one_work+0x863/0x1000 kernel/workqueue.c:2310
 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1340 [inline]
 free_pcp_prepare mm/page_alloc.c:1391 [inline]
 free_unref_page_prepare+0x637/0x6c0 mm/page_alloc.c:3317
 free_unref_page+0x94/0x280 mm/page_alloc.c:3396
 mm_free_pgd kernel/fork.c:653 [inline]
 __mmdrop+0xaa/0x3e0 kernel/fork.c:704
 free_bprm+0x141/0x300 fs/exec.c:1494
 kernel_execve+0x380/0x900 fs/exec.c:2015
 call_usermodehelper_exec_async+0x207/0x350 kernel/umh.c:112
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

Memory state around the buggy address:
 ffff888028c9a280: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff888028c9a300: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff888028c9a380: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
                                        ^
 ffff888028c9a400: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
 ffff888028c9a480: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/05/22 05:37 linux-5.15.y a68c15152131 0919b50b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: slab-out-of-bounds Read in count_subheaders
* Struck through repros no longer work on HEAD.