syzbot

==================================================================
BUG: KASAN: slab-use-after-free in ax25_find_cb+0x179/0x3a0 net/ax25/af_ax25.c:236
Read of size 8 at addr ffff888028ef6810 by task syz.0.1642/7781

CPU: 1 UID: 0 PID: 7781 Comm: syz.0.1642 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 ax25_find_cb+0x179/0x3a0 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+0x11dc/0x1ac0 net/rose/rose_subr.c:198
 rose_connect+0x909/0x10a0 net/rose/af_rose.c:881
 __sys_connect_file net/socket.c:2104 [inline]
 __sys_connect+0x316/0x440 net/socket.c:2123
 __do_sys_connect net/socket.c:2129 [inline]
 __se_sys_connect net/socket.c:2126 [inline]
 __x64_sys_connect+0x7a/0x90 net/socket.c:2126
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1c7298f749
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:00007ffd216faff8 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 00007f1c72be5fa0 RCX: 00007f1c7298f749
RDX: 0000000000000040 RSI: 0000200000000100 RDI: 0000000000000009
RBP: 00007f1c72a13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1c72be5fa0 R14: 00007f1c72be5fa0 R15: 0000000000000003
 </TASK>

Allocated by task 7745:
 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+0x3e2/0x700 mm/slub.c:5796
 kmalloc_noprof include/linux/slab.h:958 [inline]
 kzalloc_noprof include/linux/slab.h:1200 [inline]
 ax25_dev_device_up+0x54/0x600 net/ax25/ax25_dev.c:57
 ax25_device_event+0x124/0x630 net/ax25/af_ax25.c:143
 notifier_call_chain+0x19d/0x3a0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]
 call_netdevice_notifiers net/core/dev.c:2282 [inline]
 __dev_notify_flags+0x18d/0x2e0 net/core/dev.c:-1
 netif_change_flags+0xe8/0x1a0 net/core/dev.c:9804
 dev_change_flags+0x130/0x260 net/core/dev_api.c:68
 dev_ioctl+0x7b4/0x1150 net/core/dev_ioctl.c:842
 sock_do_ioctl+0x22c/0x300 net/socket.c:1283
 sock_ioctl+0x576/0x790 net/socket.c:1390
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 66:
 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:2556 [inline]
 slab_free_freelist_hook mm/slub.c:2585 [inline]
 slab_free_bulk mm/slub.c:6723 [inline]
 kmem_cache_free_bulk+0x3fb/0xdb0 mm/slub.c:7410
 kfree_bulk include/linux/slab.h:831 [inline]
 kvfree_rcu_bulk+0xe5/0x1b0 mm/slab_common.c:1523
 kfree_rcu_work+0xed/0x170 mm/slab_common.c:1601
 process_one_work+0x93a/0x15a0 kernel/workqueue.c:3279
 process_scheduled_works kernel/workqueue.c:3362 [inline]
 worker_thread+0x9b0/0xee0 kernel/workqueue.c:3443
 kthread+0x389/0x480 kernel/kthread.c:467
 ret_from_fork+0x510/0xa50 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+0x106/0x440 mm/slab_common.c:1994
 ax25_device_event+0x57e/0x630 net/ax25/af_ax25.c:148
 notifier_call_chain+0x19d/0x3a0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]
 call_netdevice_notifiers net/core/dev.c:2282 [inline]
 __dev_notify_flags+0x18d/0x2e0 net/core/dev.c:-1
 netif_change_flags+0xe8/0x1a0 net/core/dev.c:9804
 dev_change_flags+0x130/0x260 net/core/dev_api.c:68
 dev_ioctl+0x7b4/0x1150 net/core/dev_ioctl.c:842
 sock_do_ioctl+0x22c/0x300 net/socket.c:1283
 sock_ioctl+0x576/0x790 net/socket.c:1390
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888028ef6800
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 16 bytes inside of
 freed 256-byte region [ffff888028ef6800, ffff888028ef6900)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888028ef7000 pfn:0x28ef6
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
ksm flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88813fe26b40 ffffea0000c10600 dead000000000003
raw: ffff888028ef7000 000000000010000c 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88813fe26b40 ffffea0000c10600 dead000000000003
head: ffff888028ef7000 000000000010000c 00000000f5000000 0000000000000000
head: 00fff00000000001 ffffea0000a3bd81 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 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 0x52820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 24, tgid 24 (kworker/1:0), ts 109426112887, free_ts 109209163611
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x23d/0x2a0 mm/page_alloc.c:1887
 prep_new_page mm/page_alloc.c:1895 [inline]
 get_page_from_freelist+0x23a5/0x2440 mm/page_alloc.c:3948
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5257
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2486
 alloc_slab_page mm/slub.c:3091 [inline]
 allocate_slab+0x86/0x3b0 mm/slub.c:3264
 new_slab mm/slub.c:3318 [inline]
 ___slab_alloc+0xdb6/0x17b0 mm/slub.c:4672
 __slab_alloc+0x65/0x100 mm/slub.c:4795
 __slab_alloc_node mm/slub.c:4871 [inline]
 slab_alloc_node mm/slub.c:5271 [inline]
 __kmalloc_cache_noprof+0x41e/0x700 mm/slub.c:5791
 kmalloc_noprof include/linux/slab.h:958 [inline]
 kzalloc_noprof include/linux/slab.h:1200 [inline]
 br_multicast_new_group+0x155/0x13d0 net/bridge/br_multicast.c:1295
 __br_multicast_add_group+0x285/0xa30 net/bridge/br_multicast.c:1520
 br_multicast_add_group net/bridge/br_multicast.c:1569 [inline]
 br_ip6_multicast_add_group net/bridge/br_multicast.c:1621 [inline]
 br_ip6_multicast_mld2_report net/bridge/br_multicast.c:3047 [inline]
 br_multicast_ipv6_rcv net/bridge/br_multicast.c:3985 [inline]
 br_multicast_rcv+0x3a5f/0x74b0 net/bridge/br_multicast.c:4043
 br_dev_xmit+0xadd/0x1830 net/bridge/br_device.c:98
 __netdev_start_xmit include/linux/netdevice.h:5288 [inline]
 netdev_start_xmit include/linux/netdevice.h:5297 [inline]
 xmit_one net/core/dev.c:3853 [inline]
 dev_hard_start_xmit+0x2cd/0x800 net/core/dev.c:3869
 __dev_queue_xmit+0x149d/0x31c0 net/core/dev.c:4819
 NF_HOOK_COND include/linux/netfilter.h:307 [inline]
 ip6_output+0x340/0x550 net/ipv6/ip6_output.c:247
 NF_HOOK+0x9e/0x380 include/linux/netfilter.h:318
page last free pid 23 tgid 23 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1436 [inline]
 __free_frozen_pages+0xb99/0xd10 mm/page_alloc.c:2976
 rcu_do_batch kernel/rcu/tree.c:2617 [inline]
 rcu_core+0x7bd/0x1060 kernel/rcu/tree.c:2869
 handle_softirqs+0x22b/0x7c0 kernel/softirq.c:626
 run_ksoftirqd+0x36/0x60 kernel/softirq.c:1067
 smpboot_thread_fn+0x542/0xa60 kernel/smpboot.c:160
 kthread+0x389/0x480 kernel/kthread.c:467
 ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

Memory state around the buggy address:
 ffff888028ef6700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888028ef6780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888028ef6800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff888028ef6880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888028ef6900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================