KASAN: slab-use-after-free Read in ax25_find_cb

Status: auto-obsoleted due to no activity on 2026/10/14 18:44
Subsystems: hams
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+caa052a0958a9146870d@syzkaller.appspotmail.com
First crash: 365d, last: 189d
Cause bisection: failed (error log, bisect log)
  
Fix bisection: failed (error log, bisect log)
  
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
f83775cd assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ❌ NetworkTrigger: ✅ PeripheralTrigger: ✅ RemoteTrigger: ✅ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ✅ VMHostTrigger: ❌ ❓ KASAN: slab-use-after-free Read in ax25_find_cb 2026/05/30 17:02 2026/05/30 17:02 2026/05/30 18:05 6b4a8443
1e40a5b7 assessment-security 💥 KASAN: slab-use-after-free Read in ax25_find_cb 2026/05/14 11:11 2026/05/14 11:11 2026/05/14 11:12 6ccb967e
▶ ▼ Discussions (6)
Title Replies (including bot) Last reply
[syzbot] Monthly hams report (Feb 2026) 0 (1) 2026/02/26 12:58
[syzbot] Monthly hams report (Dec 2025) 0 (1) 2025/12/26 07:48
[syzbot] [hams?] KASAN: slab-use-after-free Read in ax25_find_cb 0 (2) 2025/12/09 10:34
[PATCH V3] net: rose: Prevent the use of freed digipeat 11 (11) 2025/10/28 02:05
[PATCH] net: rose: Prevent the use of freed digipeat 4 (4) 2025/10/24 23:58
[PATCH V2] net: rose: Prevent the use of freed digipeat 2 (2) 2025/10/24 09:19
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 KASAN: slab-use-after-free Read in ax25_find_cb origin:upstream missing-backport 19 syz, C inconclusive 1 128d 318d 0/2 upstream: reported C repro on 2025/12/08 04:33
linux-5.15 KASAN: use-after-free Read in ax25_find_cb (2) 19 41 225d 226d 0/3 auto-obsoleted due to no activity on 2026/05/21 01:11
linux-5.15 KASAN: use-after-free Read in ax25_find_cb 19 3 426d 457d 0/3 auto-obsoleted due to no activity on 2025/11/30 02:07
linux-6.1 KASAN: use-after-free Read in ax25_find_cb origin:upstream missing-backport 19 syz error 1 347d 347d 0/3 upstream: reported syz repro on 2025/11/09 13:50
▶ ▼ Last patch testing requests (10)
Created Duration User Patch Repo Result
2026/10/12 23:25 28m retest repro linux-next no crash job log log
2026/10/12 23:25 29m retest repro linux-next no crash job log log
2026/10/12 23:25 29m retest repro linux-next no crash job log log
2026/10/08 15:51 2h11m retest repro net no crash job log log
2026/08/02 14:51 9m retest repro linux-next error
2026/08/02 14:51 12m retest repro linux-next error
2026/08/02 14:51 12m retest repro linux-next error
2026/07/25 23:08 1h49m retest repro net log
2026/07/18 05:28 27m retest repro upstream no crash log
2026/05/24 11:32 34m retest repro linux-next log

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in ax25_find_cb+0x18e/0x3e0 net/ax25/af_ax25.c:236
Read of size 8 at addr ffff88802ee94a10 by task syz.0.1505/10152

CPU: 1 UID: 0 PID: 10152 Comm: syz.0.1505 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/13/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 ax25_find_cb+0x18e/0x3e0 net/ax25/af_ax25.c:236
 rose_link_up net/rose/rose_link.c:129 [inline]
 rose_transmit_link+0x16d/0x740 net/rose/rose_link.c:271
 rose_write_internal+0x1256/0x1b60 net/rose/rose_subr.c:198
 rose_release+0x2e3/0x5c0 net/rose/af_rose.c:671
 __sock_release net/socket.c:662 [inline]
 sock_close+0xc3/0x240 net/socket.c:1455
 __fput+0x45e/0xa80 fs/file_table.c:468
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 get_signal+0x11c3/0x1310 kernel/signal.c:2807
 arch_do_signal_or_restart+0xbc/0x830 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:41 [inline]
 exit_to_user_mode_loop+0x86/0x480 kernel/entry/common.c:75
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
 do_syscall_64+0x2b7/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fadf31dacb9
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:00007fadf1415028 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: fffffffffffffe00 RBX: 00007fadf3456090 RCX: 00007fadf31dacb9
RDX: 0000000000000040 RSI: 0000200000000100 RDI: 000000000000000e
RBP: 00007fadf3248bf7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fadf3456128 R14: 00007fadf3456090 R15: 00007ffe4f31a838
 </TASK>

Allocated by task 10138:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __kmalloc_cache_noprof+0x1f2/0x6b0 mm/slub.c:5780
 kmalloc_noprof include/linux/slab.h:957 [inline]
 kzalloc_noprof include/linux/slab.h:1094 [inline]
 ax25_dev_device_up+0x54/0x610 net/ax25/ax25_dev.c:57
 ax25_device_event+0x124/0x670 net/ax25/af_ax25.c:143
 notifier_call_chain+0x19d/0x3a0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2281 [inline]
 call_netdevice_notifiers net/core/dev.c:2295 [inline]
 __dev_notify_flags+0x1a9/0x310 net/core/dev.c:9788
 netif_change_flags+0xe8/0x1a0 net/core/dev.c:9817
 dev_change_flags+0x130/0x260 net/core/dev_api.c:68
 dev_ioctl+0x7b4/0x1150 net/core/dev_ioctl.c:842
 sock_do_ioctl+0x23e/0x320 net/socket.c:1268
 sock_ioctl+0x5c9/0x7f0 net/socket.c:1375
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xff/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 5940:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2540 [inline]
 slab_free_freelist_hook mm/slub.c:2569 [inline]
 slab_free_bulk mm/slub.c:6707 [inline]
 kmem_cache_free_bulk+0xa82/0x10e0 mm/slub.c:7394
 kfree_bulk include/linux/slab.h:830 [inline]
 kvfree_rcu_bulk+0xe5/0x1f0 mm/slab_common.c:1523
 kfree_rcu_work+0xed/0x170 mm/slab_common.c:1601
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0xaec/0x17a0 kernel/workqueue.c:3340
 worker_thread+0x89f/0xd90 kernel/workqueue.c:3421
 kthread+0x726/0x8b0 kernel/kthread.c:463
 ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

Last potentially related work creation:
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:57
 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556
 kvfree_call_rcu+0x90/0x3c0 mm/slab_common.c:1994
 ax25_device_event+0x5c0/0x670 net/ax25/af_ax25.c:148
 notifier_call_chain+0x19d/0x3a0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2281 [inline]
 call_netdevice_notifiers net/core/dev.c:2295 [inline]
 __dev_notify_flags+0x16d/0x310 net/core/dev.c:9790
 netif_change_flags+0xe8/0x1a0 net/core/dev.c:9817
 dev_change_flags+0x130/0x260 net/core/dev_api.c:68
 dev_ioctl+0x7b4/0x1150 net/core/dev_ioctl.c:842
 sock_do_ioctl+0x23e/0x320 net/socket.c:1268
 sock_ioctl+0x5c9/0x7f0 net/socket.c:1375
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xff/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88802ee94a00
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 16 bytes inside of
 freed 256-byte region [ffff88802ee94a00, ffff88802ee94b00)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2ee94
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x80000000000040(head|node=0|zone=1)
page_type: f5(slab)
raw: 0080000000000040 ffff88813fea6b40 ffffea0001850500 dead000000000002
raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 0080000000000040 ffff88813fea6b40 ffffea0001850500 dead000000000002
head: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 0080000000000001 ffffea0000bba501 00000000ffffffff 00000000ffffffff
head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000002
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 23525004009, free_ts 0
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x228/0x280 mm/page_alloc.c:1884
 prep_new_page mm/page_alloc.c:1892 [inline]
 get_page_from_freelist+0x28bb/0x2950 mm/page_alloc.c:3945
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5240
 alloc_pages_mpol+0xd1/0x380 mm/mempolicy.c:2486
 alloc_slab_page mm/slub.c:3075 [inline]
 allocate_slab+0x86/0x3a0 mm/slub.c:3248
 new_slab mm/slub.c:3302 [inline]
 ___slab_alloc+0xaf8/0x13d0 mm/slub.c:4656
 __slab_alloc+0xc5/0x1f0 mm/slub.c:4779
 __slab_alloc_node mm/slub.c:4855 [inline]
 slab_alloc_node mm/slub.c:5251 [inline]
 __do_kmalloc_node mm/slub.c:5656 [inline]
 __kvmalloc_node_noprof+0x2f9/0x8f0 mm/slub.c:7140
 v4l2_ctrl_new+0x9d5/0x1790 drivers/media/v4l2-core/v4l2-ctrls-core.c:2112
 v4l2_ctrl_new_std+0x24e/0x300 drivers/media/v4l2-core/v4l2-ctrls-core.c:2266
 handler_new_ref+0x153/0x9c0 drivers/media/v4l2-core/v4l2-ctrls-core.c:1853
 v4l2_ctrl_add_handler+0x19f/0x290 drivers/media/v4l2-core/v4l2-ctrls-core.c:2416
 vivid_create_controls+0x324b/0x3bd0 drivers/media/test-drivers/vivid/vivid-ctrls.c:2065
 vivid_create_instance drivers/media/test-drivers/vivid/vivid-core.c:1933 [inline]
 vivid_probe+0x425f/0x72c0 drivers/media/test-drivers/vivid/vivid-core.c:2095
 platform_probe+0xf9/0x190 drivers/base/platform.c:1446
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x26d/0xac0 drivers/base/dd.c:659
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88802ee94900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88802ee94980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88802ee94a00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff88802ee94a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88802ee94b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (14):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/24 16:31 upstream 62085877ae65 40acda8a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root KASAN: slab-use-after-free Read in ax25_find_cb
2025/10/22 18:31 upstream 250a17e8f955 252fbbad .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root KASAN: slab-use-after-free Read in ax25_find_cb
2026/02/08 14:56 upstream e7aa57247700 4c131dc4 .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: slab-use-after-free Read in ax25_find_cb
2026/04/16 07:17 net 1f5ffc672165 df15c5f3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce KASAN: slab-use-after-free Read in ax25_find_cb
2026/04/04 06:47 net 1979645e1842 4440e7c2 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce KASAN: slab-use-after-free Read in ax25_find_cb
2026/02/14 04:41 net ee5492fd88cf 1e62d198 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce KASAN: slab-use-after-free Read in ax25_find_cb
2026/01/27 06:23 net 8d7ba71e4621 efb3e894 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce KASAN: slab-use-after-free Read in ax25_find_cb
2026/03/01 08:41 net-next 01857fc712f6 43249bac .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce KASAN: slab-use-after-free Read in ax25_find_cb
2026/03/22 04:52 linux-next 785f0eb2f85d 5b92003d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: slab-use-after-free Read in ax25_find_cb
2026/01/12 07:57 linux-next f417b7ffcbef d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce KASAN: slab-use-after-free Read in ax25_find_cb
2026/01/12 04:30 linux-next f417b7ffcbef d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: slab-use-after-free Read in ax25_find_cb
2026/01/11 03:44 linux-next f417b7ffcbef d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce KASAN: slab-use-after-free Read in ax25_find_cb
2026/01/10 23:59 linux-next f417b7ffcbef d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: slab-use-after-free Read in ax25_find_cb
2025/12/09 10:34 linux-next c75caf76ed86 d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce KASAN: slab-use-after-free Read in ax25_find_cb
* Struck through repros no longer work on HEAD.