================================================================== BUG: KASAN: slab-use-after-free in ax25_find_cb+0x179/0x3a0 net/ax25/af_ax25.c:236 Read of size 8 at addr ffff88807ae03c10 by task syz.2.1873/7945 CPU: 1 UID: 0 PID: 7945 Comm: syz.2.1873 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 Call Trace: 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+0x179/0x3a0 net/ax25/af_ax25.c:236 rose_link_up net/rose/rose_link.c:129 [inline] rose_transmit_link+0x17b/0xac0 net/rose/rose_link.c:271 rose_write_internal+0x1256/0x1b60 net/rose/rose_subr.c:198 rose_connect+0x95c/0x10b0 net/rose/af_rose.c:886 __sys_connect_file net/socket.c:2148 [inline] __sys_connect+0x312/0x450 net/socket.c:2167 __do_sys_connect net/socket.c:2173 [inline] __se_sys_connect net/socket.c:2170 [inline] __x64_sys_connect+0x7a/0x90 net/socket.c:2170 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: 0033:0x7f83fc79c819 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:00007ffff5d568c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002a RAX: ffffffffffffffda RBX: 00007f83fca15fa0 RCX: 00007f83fc79c819 RDX: 0000000000000040 RSI: 0000200000000100 RDI: 0000000000000009 RBP: 00007f83fc832c91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f83fca15fac R14: 00007f83fca15fa0 R15: 00007f83fca15fa0 Allocated by task 7929: 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:5380 kmalloc_noprof include/linux/slab.h:950 [inline] kzalloc_noprof include/linux/slab.h:1188 [inline] ax25_dev_device_up+0x54/0x5f0 net/ax25/ax25_dev.c:57 ax25_device_event+0x127/0x8a0 net/ax25/af_ax25.c:143 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] __dev_notify_flags+0x1a9/0x310 net/core/dev.c:9849 netif_change_flags+0xe8/0x1a0 net/core/dev.c:9878 dev_change_flags+0x130/0x260 net/core/dev_api.c:68 dev_ioctl+0x7b4/0x1150 net/core/dev_ioctl.c:814 sock_do_ioctl+0x23e/0x320 net/socket.c:1327 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 23: 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:2685 [inline] __rcu_free_sheaf_prepare+0x129/0x290 mm/slub.c:2954 rcu_free_sheaf+0x31/0x200 mm/slub.c:5811 rcu_do_batch kernel/rcu/tree.c:2617 [inline] rcu_core+0x7cd/0x1070 kernel/rcu/tree.c:2869 handle_softirqs+0x22a/0x840 kernel/softirq.c:622 run_ksoftirqd+0x36/0x60 kernel/softirq.c:1076 smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 The buggy address belongs to the object at ffff88807ae03c00 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 16 bytes inside of freed 256-byte region [ffff88807ae03c00, ffff88807ae03d00) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88807ae02800 pfn:0x7ae02 head: order:1 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 ffff88813fe2cb40 ffffea0001ea6790 ffffea0000d0d990 raw: ffff88807ae02800 000000080010000f 00000000f5000000 0000000000000000 head: 00fff00000000240 ffff88813fe2cb40 ffffea0001ea6790 ffffea0000d0d990 head: ffff88807ae02800 000000080010000f 00000000f5000000 0000000000000000 head: 00fff00000000001 ffffea0001eb8081 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5947, tgid 5947 (syz-executor), ts 105885415435, free_ts 105834821774 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889 prep_new_page mm/page_alloc.c:1897 [inline] get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250 alloc_slab_page mm/slub.c:3292 [inline] allocate_slab+0x77/0x660 mm/slub.c:3481 new_slab mm/slub.c:3539 [inline] refill_objects+0x331/0x3c0 mm/slub.c:7175 refill_sheaf mm/slub.c:2812 [inline] __pcs_replace_empty_main+0x2e6/0x730 mm/slub.c:4615 alloc_from_pcs mm/slub.c:4717 [inline] slab_alloc_node mm/slub.c:4851 [inline] __do_kmalloc_node mm/slub.c:5259 [inline] __kmalloc_noprof+0x474/0x760 mm/slub.c:5272 kmalloc_noprof include/linux/slab.h:954 [inline] kzalloc_noprof include/linux/slab.h:1188 [inline] fib_create_info+0x1723/0x31f0 net/ipv4/fib_semantics.c:1400 fib_table_insert+0xc8/0x1b50 net/ipv4/fib_trie.c:1212 fib_magic+0x434/0x510 net/ipv4/fib_frontend.c:1134 fib_add_ifaddr+0x38d/0x5f0 net/ipv4/fib_frontend.c:1171 fib_netdev_event+0x382/0x490 net/ipv4/fib_frontend.c:1516 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] __dev_notify_flags+0x1a9/0x310 net/core/dev.c:9849 netif_change_flags+0xe8/0x1a0 net/core/dev.c:9878 do_setlink+0xf82/0x4590 net/core/rtnetlink.c:3180 page last free pid 0 tgid 0 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1433 [inline] __free_frozen_pages+0xc2b/0xdb0 mm/page_alloc.c:2978 rcu_do_batch kernel/rcu/tree.c:2617 [inline] rcu_core+0x7cd/0x1070 kernel/rcu/tree.c:2869 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 Memory state around the buggy address: ffff88807ae03b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88807ae03b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88807ae03c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88807ae03c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88807ae03d00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================