==================================================================
BUG: KASAN: slab-use-after-free in ax25_send_frame+0x67c/0x9f0 net/ax25/ax25_out.c:75
Read of size 7 at addr ffff88805451e808 by task syz-executor/29847

CPU: 1 UID: 0 PID: 29847 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
 <IRQ>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x264/0x2c0 mm/kasan/generic.c:200
 __asan_memcpy+0x29/0x70 mm/kasan/shadow.c:105
 ax25_send_frame+0x67c/0x9f0 net/ax25/ax25_out.c:75
 rose_send_frame net/rose/rose_link.c:106 [inline]
 rose_transmit_restart_request net/rose/rose_link.c:198 [inline]
 rose_t0timer_expiry+0x255/0x560 net/rose/rose_link.c:83
 call_timer_fn+0x192/0x5e0 kernel/time/timer.c:1748
 expire_timers kernel/time/timer.c:1799 [inline]
 __run_timers kernel/time/timer.c:2374 [inline]
 __run_timer_base+0x652/0x8b0 kernel/time/timer.c:2386
 run_timer_base kernel/time/timer.c:2395 [inline]
 run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2405
 handle_softirqs+0x22a/0x840 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0xca/0x220 kernel/softirq.c:735
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:752
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
 sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1061
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:rwsem_set_owner kernel/locking/rwsem.c:143 [inline]
RIP: 0010:rwsem_write_trylock kernel/locking/rwsem.c:269 [inline]
RIP: 0010:__down_write_common kernel/locking/rwsem.c:1346 [inline]
RIP: 0010:__down_write kernel/locking/rwsem.c:1356 [inline]
RIP: 0010:down_write+0x103/0x200 kernel/locking/rwsem.c:1626
Code: 0f b1 0b 0f 85 c7 00 00 00 48 c7 c0 c0 b9 33 90 48 c1 e8 03 42 0f b6 04 38 84 c0 0f 85 d9 00 00 00 83 3d 6f ee 78 04 00 74 28 <65> 8b 05 56 4a 86 07 85 c0 75 1d 65 8b 05 cb 04 86 07 a9 ff ff ff
RSP: 0018:ffffc9000547fcc0 EFLAGS: 00000202
RAX: 0000000000000000 RBX: ffff888025836298 RCX: 0000000000000001
RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffffc9000547fce0
RBP: ffffc9000547fd40 R08: ffffc9000547fce7 R09: 1ffff92000a8ff9c
R10: dffffc0000000000 R11: fffff52000a8ff9d R12: 1ffff92000a8ff98
R13: 1ffff11005e13573 R14: ffffc9000547fce0 R15: dffffc0000000000
 inode_lock include/linux/fs.h:1029 [inline]
 vfs_unlink+0xed/0x6c0 fs/namei.c:5484
 filename_unlinkat+0x3cd/0x610 fs/namei.c:5568
 __do_sys_unlink fs/namei.c:5603 [inline]
 __se_sys_unlink+0x2e/0x140 fs/namei.c:5600
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5d2cf9bec7
Code: 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 57 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007fff96823798 EFLAGS: 00000206 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f5d2cf9bec7
RDX: 00007fff968237c0 RSI: 00007fff96823850 RDI: 00007fff96823850
RBP: 00007fff96823850 R08: 00007fff96824850 R09: 00000000ffffffff
R10: 0000000000000100 R11: 0000000000000206 R12: 00007fff968248e0
R13: 00007f5d2d032120 R14: 00000000000e49f5 R15: 00007fff96824920
 </TASK>

Allocated by task 28716:
 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+0x31c/0x660 mm/slub.c:5415
 kmalloc_noprof include/linux/slab.h:950 [inline]
 rose_add_node+0x23c/0xf00 net/rose/rose_route.c:85
 rose_rt_ioctl+0xd35/0x12a0 net/rose/rose_route.c:748
 rose_ioctl+0x3fb/0x8f0 net/rose/af_rose.c:1387
 sock_do_ioctl+0x101/0x320 net/socket.c:1313
 sock_ioctl+0x5c6/0x7f0 net/socket.c:1434
 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+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 4341:
 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:2689 [inline]
 slab_free mm/slub.c:6246 [inline]
 kfree+0x1c5/0x640 mm/slub.c:6561
 rose_neigh_put include/net/rose.h:166 [inline]
 rose_timer_expiry+0x4cb/0x600 net/rose/rose_timer.c:183
 call_timer_fn+0x192/0x5e0 kernel/time/timer.c:1748
 expire_timers kernel/time/timer.c:1799 [inline]
 __run_timers kernel/time/timer.c:2374 [inline]
 __run_timer_base+0x652/0x8b0 kernel/time/timer.c:2386
 run_timer_base kernel/time/timer.c:2395 [inline]
 run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2405
 handle_softirqs+0x22a/0x840 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0xca/0x220 kernel/softirq.c:735
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:752
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
 sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1061
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697

The buggy address belongs to the object at ffff88805451e800
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 8 bytes inside of
 freed 512-byte region [ffff88805451e800, ffff88805451ea00)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88805451ec00 pfn:0x5451c
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000240(workingset|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000240 ffff88813fe2ec80 ffffea000072d710 ffffea0001518110
raw: ffff88805451ec00 0000000800100005 00000000f5000000 0000000000000000
head: 00fff00000000240 ffff88813fe2ec80 ffffea000072d710 ffffea0001518110
head: ffff88805451ec00 0000000800100005 00000000f5000000 0000000000000000
head: 00fff00000000002 ffffffffffffff01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 6885, tgid 6881 (syz.1.191), ts 106525117532, free_ts 106511906148
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1858
 prep_new_page mm/page_alloc.c:1866 [inline]
 get_page_from_freelist+0x24ba/0x2540 mm/page_alloc.c:3946
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5226
 alloc_slab_page mm/slub.c:3278 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3467
 new_slab mm/slub.c:3525 [inline]
 refill_objects+0x339/0x3d0 mm/slub.c:7251
 refill_sheaf mm/slub.c:2816 [inline]
 __pcs_replace_empty_main+0x321/0x720 mm/slub.c:4651
 alloc_from_pcs mm/slub.c:4749 [inline]
 slab_alloc_node mm/slub.c:4883 [inline]
 __do_kmalloc_node mm/slub.c:5294 [inline]
 __kmalloc_noprof+0x474/0x760 mm/slub.c:5307
 kmalloc_noprof include/linux/slab.h:954 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 tnode_alloc net/ipv4/fib_trie.c:327 [inline]
 tnode_new+0xc3/0x3b0 net/ipv4/fib_trie.c:380
 inflate net/ipv4/fib_trie.c:594 [inline]
 resize+0x826/0x2590 net/ipv4/fib_trie.c:864
 trie_rebalance net/ipv4/fib_trie.c:1101 [inline]
 fib_insert_node net/ipv4/fib_trie.c:1145 [inline]
 fib_insert_alias+0xdb3/0x1100 net/ipv4/fib_trie.c:1159
 fib_trie_unmerge+0x310/0xcd0 net/ipv4/fib_trie.c:1910
 fib_unmerge+0xc5/0x360 net/ipv4/fib_frontend.c:162
 fib4_rule_configure+0x2e2/0xa50 net/ipv4/fib_rules.c:305
 fib_newrule+0x5d0/0x1030 net/core/fib_rules.c:920
 rtnetlink_rcv_msg+0x7d5/0xbe0 net/core/rtnetlink.c:6995
 netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550
page last free pid 6882 tgid 6881 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1402 [inline]
 __free_frozen_pages+0xbc7/0xd30 mm/page_alloc.c:2943
 stack_depot_save_flags+0x40e/0x810 lib/stackdepot.c:735
 kasan_save_stack mm/kasan/common.c:58 [inline]
 kasan_save_track+0x4f/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+0x31c/0x660 mm/slub.c:5415
 kmalloc_noprof include/linux/slab.h:950 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 mca_alloc net/ipv6/mcast.c:871 [inline]
 __ipv6_dev_mc_inc+0x44f/0xa50 net/ipv6/mcast.c:961
 ipv6_add_dev+0xe34/0x13a0 net/ipv6/addrconf.c:472
 addrconf_notify+0x771/0x1050 net/ipv6/addrconf.c:3662
 notifier_call_chain+0x1ad/0x3d0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2287 [inline]
 call_netdevice_notifiers net/core/dev.c:2301 [inline]
 register_netdevice+0x18c9/0x1ec0 net/core/dev.c:11465
 ip6gre_newlink_common+0x403/0x5b0 net/ipv6/ip6_gre.c:1966
 ip6erspan_newlink+0x48b/0x870 net/ipv6/ip6_gre.c:2238
 rtnl_newlink_create+0x329/0xb70 net/core/rtnetlink.c:3863
 __rtnl_newlink net/core/rtnetlink.c:3994 [inline]
 rtnl_newlink+0x166a/0x1bb0 net/core/rtnetlink.c:4109
 rtnetlink_rcv_msg+0x7d5/0xbe0 net/core/rtnetlink.c:6995
 netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550

Memory state around the buggy address:
 ffff88805451e700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88805451e780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88805451e800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff88805451e880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88805451e900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess):
   0:	0f b1 0b             	cmpxchg %ecx,(%rbx)
   3:	0f 85 c7 00 00 00    	jne    0xd0
   9:	48 c7 c0 c0 b9 33 90 	mov    $0xffffffff9033b9c0,%rax
  10:	48 c1 e8 03          	shr    $0x3,%rax
  14:	42 0f b6 04 38       	movzbl (%rax,%r15,1),%eax
  19:	84 c0                	test   %al,%al
  1b:	0f 85 d9 00 00 00    	jne    0xfa
  21:	83 3d 6f ee 78 04 00 	cmpl   $0x0,0x478ee6f(%rip)        # 0x478ee97
  28:	74 28                	je     0x52
* 2a:	65 8b 05 56 4a 86 07 	mov    %gs:0x7864a56(%rip),%eax        # 0x7864a87 <-- trapping instruction
  31:	85 c0                	test   %eax,%eax
  33:	75 1d                	jne    0x52
  35:	65 8b 05 cb 04 86 07 	mov    %gs:0x78604cb(%rip),%eax        # 0x7860507
  3c:	a9                   	.byte 0xa9
  3d:	ff                   	(bad)
  3e:	ff                   	(bad)
  3f:	ff                   	.byte 0xff