================================================================== BUG: KASAN: use-after-free in ax25_heartbeat_expiry+0x10c/0x130 net/ax25/ax25_timer.c:125 Read of size 4 at addr ffff888023dc8550 by task syz.1.196/5139 CPU: 1 PID: 5139 Comm: syz.1.196 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Call Trace: dump_stack_lvl+0x188/0x250 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 ax25_heartbeat_expiry+0x10c/0x130 net/ax25/ax25_timer.c:125 call_timer_fn+0x17b/0x540 kernel/time/timer.c:1648 expire_timers kernel/time/timer.c:1699 [inline] __run_timers+0x53e/0x800 kernel/time/timer.c:1970 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1983 handle_softirqs+0x339/0x830 kernel/softirq.c:576 __do_softirq kernel/softirq.c:610 [inline] invoke_softirq kernel/softirq.c:450 [inline] __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:659 irq_exit_rcu+0x5/0x20 kernel/softirq.c:671 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline] sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676 RIP: 0010:finish_lock_switch+0x134/0x280 kernel/sched/core.c:4804 Code: be ff ff ff ff e8 6c 01 68 08 85 c0 74 4a 4d 85 ff 75 66 e9 fe 00 00 00 48 89 df e8 16 6d 71 08 e8 f1 e2 2a 00 fb 48 83 c4 08 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 48 89 df e8 c9 09 fe ff 43 80 3c RSP: 0000:ffffc9000396f2c8 EFLAGS: 00000282 RAX: 7fc4cdac52fef400 RBX: ffff8880b903a340 RCX: 7fc4cdac52fef400 RDX: dffffc0000000000 RSI: ffffffff8a2b2780 RDI: ffffffff8a79f980 RBP: 1ffff11017227613 R08: ffff8880b903a343 R09: 1ffff11017207468 R10: dffffc0000000000 R11: ffffed1017207469 R12: ffff8880b913b088 R13: dffffc0000000000 R14: ffff8880b913ae08 R15: 0000000000000000 finish_task_switch+0x12f/0x640 kernel/sched/core.c:4921 context_switch kernel/sched/core.c:5052 [inline] __schedule+0x11f7/0x43c0 kernel/sched/core.c:6395 schedule+0x11b/0x1e0 kernel/sched/core.c:6478 schedule_timeout+0xbd/0x2d0 kernel/time/timer.c:2093 unix_wait_for_peer+0x1f2/0x2e0 net/unix/af_unix.c:1315 unix_dgram_sendmsg+0x1083/0x18a0 net/unix/af_unix.c:1910 sock_sendmsg_nosec net/socket.c:706 [inline] __sock_sendmsg net/socket.c:718 [inline] ____sys_sendmsg+0x5b7/0x8f0 net/socket.c:2445 ___sys_sendmsg+0x236/0x2e0 net/socket.c:2499 __sys_sendmmsg+0x2ba/0x500 net/socket.c:2585 __do_sys_sendmmsg net/socket.c:2614 [inline] __se_sys_sendmmsg net/socket.c:2611 [inline] __x64_sys_sendmmsg+0x9c/0xb0 net/socket.c:2611 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: 0033:0x7fd3edcc0799 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:00007fd3ebf1a028 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 00007fd3edf39fa0 RCX: 00007fd3edcc0799 RDX: 0000000000000318 RSI: 00002000000bd000 RDI: 0000000000000005 RBP: 00007fd3edd56c99 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fd3edf3a038 R14: 00007fd3edf39fa0 R15: 00007ffe3b9e0ca8 Allocated by task 4332: 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:607 [inline] kzalloc include/linux/slab.h:738 [inline] ax25_dev_device_up+0x50/0x580 net/ax25/ax25_dev.c:55 ax25_device_event+0x483/0x4f0 net/ax25/af_ax25.c:139 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:2074 [inline] call_netdevice_notifiers net/core/dev.c:2088 [inline] __dev_notify_flags+0x194/0x300 net/core/dev.c:8917 dev_change_flags+0xe3/0x1a0 net/core/dev.c:8955 dev_ifsioc+0x130/0xd50 net/core/dev_ioctl.c:324 dev_ioctl+0x545/0xe30 net/core/dev_ioctl.c:572 sock_do_ioctl+0x245/0x320 net/socket.c:1161 sock_ioctl+0x4d2/0x710 net/socket.c:1266 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 Freed by task 5125: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:46 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360 ____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366 kasan_slab_free include/linux/kasan.h:230 [inline] slab_free_hook mm/slub.c:1710 [inline] slab_free_freelist_hook+0xea/0x170 mm/slub.c:1736 slab_free mm/slub.c:3504 [inline] kfree+0xef/0x2a0 mm/slub.c:4564 ax25_dev_put include/net/ax25.h:302 [inline] ax25_release+0x661/0x870 net/ax25/af_ax25.c:1062 __sock_release net/socket.c:651 [inline] sock_close+0xd5/0x240 net/socket.c:1345 __fput+0x234/0x930 fs/file_table.c:311 task_work_run+0x125/0x1a0 kernel/task_work.c:188 exit_task_work include/linux/task_work.h:33 [inline] do_exit+0x626/0x20c0 kernel/exit.c:883 do_group_exit+0x12e/0x300 kernel/exit.c:997 get_signal+0x6ca/0x12c0 kernel/signal.c:2900 arch_do_signal_or_restart+0xe7/0x12c0 arch/x86/kernel/signal.c:867 handle_signal_work kernel/entry/common.c:154 [inline] exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:178 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307 ret_from_fork+0x15/0x30 arch/x86/entry/entry_64.S:280 The buggy address belongs to the object at ffff888023dc8500 which belongs to the cache kmalloc-192 of size 192 The buggy address is located 80 bytes inside of 192-byte region [ffff888023dc8500, ffff888023dc85c0) The buggy address belongs to the page: page:ffffea00008f7200 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888023dc8f00 pfn:0x23dc8 flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000000200 ffffea0000910dc8 ffffea0000ae2108 ffff888016c41a00 raw: ffff888023dc8f00 000000000010000e 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 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 4193, ts 80916394922, free_ts 80915798635 prep_new_page mm/page_alloc.c:2426 [inline] get_page_from_freelist+0x1bbd/0x1ca0 mm/page_alloc.c:4192 __alloc_pages+0x1ee/0x480 mm/page_alloc.c:5501 __alloc_pages_node include/linux/gfp.h:570 [inline] alloc_slab_page mm/slub.c:1782 [inline] allocate_slab mm/slub.c:1917 [inline] new_slab+0xb6/0x4b0 mm/slub.c:1980 ___slab_alloc+0x80a/0xdd0 mm/slub.c:3013 __slab_alloc mm/slub.c:3100 [inline] slab_alloc_node mm/slub.c:3191 [inline] __kmalloc_node+0x200/0x3b0 mm/slub.c:4456 kmalloc_array_node include/linux/slab.h:700 [inline] kcalloc_node include/linux/slab.h:705 [inline] memcg_alloc_page_obj_cgroups+0x81/0x120 mm/memcontrol.c:2839 memcg_slab_post_alloc_hook mm/slab.h:313 [inline] slab_post_alloc_hook+0xba/0x380 mm/slab.h:526 slab_alloc_node mm/slub.c:3225 [inline] slab_alloc mm/slub.c:3233 [inline] kmem_cache_alloc+0x100/0x290 mm/slub.c:3238 sock_alloc_inode+0x17/0xb0 net/socket.c:305 alloc_inode fs/inode.c:261 [inline] new_inode_pseudo+0x5f/0x210 fs/inode.c:1001 sock_alloc net/socket.c:628 [inline] __sock_create+0x129/0x900 net/socket.c:1459 sock_create net/socket.c:1551 [inline] __sys_socket+0xe2/0x170 net/socket.c:1593 __do_sys_socket net/socket.c:1602 [inline] __se_sys_socket net/socket.c:1600 [inline] __x64_sys_socket+0x76/0x80 net/socket.c:1600 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 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+0x8f/0x2a0 mm/page_alloc.c:3396 __vunmap+0x8b9/0xa50 mm/vmalloc.c:2628 __do_replace+0x84c/0x9b0 net/ipv4/netfilter/ip_tables.c:1091 do_replace net/ipv4/netfilter/ip_tables.c:1142 [inline] do_ipt_set_ctl+0xaa1/0xd80 net/ipv4/netfilter/ip_tables.c:1636 nf_setsockopt+0x25f/0x280 net/netfilter/nf_sockopt.c:101 ip_setsockopt+0x207d/0x3130 net/ipv4/ip_sockglue.c:1442 tcp_setsockopt+0x240/0x1e90 net/ipv4/tcp.c:3722 __sys_setsockopt+0x2bf/0x3d0 net/socket.c:2212 __do_sys_setsockopt net/socket.c:2223 [inline] __se_sys_setsockopt net/socket.c:2220 [inline] __x64_sys_setsockopt+0xb1/0xc0 net/socket.c:2220 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 Memory state around the buggy address: ffff888023dc8400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888023dc8480: 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888023dc8500: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888023dc8580: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ffff888023dc8600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ================================================================== ---------------- Code disassembly (best guess): 0: be ff ff ff ff mov $0xffffffff,%esi 5: e8 6c 01 68 08 call 0x8680176 a: 85 c0 test %eax,%eax c: 74 4a je 0x58 e: 4d 85 ff test %r15,%r15 11: 75 66 jne 0x79 13: e9 fe 00 00 00 jmp 0x116 18: 48 89 df mov %rbx,%rdi 1b: e8 16 6d 71 08 call 0x8716d36 20: e8 f1 e2 2a 00 call 0x2ae316 25: fb sti 26: 48 83 c4 08 add $0x8,%rsp * 2a: 5b pop %rbx <-- trapping instruction 2b: 41 5c pop %r12 2d: 41 5d pop %r13 2f: 41 5e pop %r14 31: 41 5f pop %r15 33: 5d pop %rbp 34: c3 ret 35: 48 89 df mov %rbx,%rdi 38: e8 c9 09 fe ff call 0xfffe0a06 3d: 43 rex.XB 3e: 80 .byte 0x80 3f: 3c .byte 0x3c