================================================================== BUG: KASAN: slab-use-after-free in ax25_find_cb+0x179/0x3a0 net/ax25/af_ax25.c:236 Read of size 8 at addr ffff888076670610 by task syz.8.2479/17427 CPU: 1 UID: 0 PID: 17427 Comm: syz.8.2479 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Call Trace: 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 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_release+0x2be/0x590 net/rose/af_rose.c:671 __sock_release+0xb9/0x250 net/socket.c:725 sock_close+0x1c/0x30 net/socket.c:1528 __fput+0x451/0x8c0 fs/file_table.c:500 task_work_run+0x1d9/0x270 kernel/task_work.c:233 get_signal+0x11eb/0x1330 kernel/signal.c:2809 arch_do_signal_or_restart+0xbc/0x830 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline] exit_to_user_mode_loop+0x86/0x480 kernel/entry/common.c:98 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:269 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline] do_syscall_64+0x32d/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f6c3e99c799 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:00007f6c3f7ac028 EFLAGS: 00000246 ORIG_RAX: 000000000000002a RAX: fffffffffffffe00 RBX: 00007f6c3ec15fa0 RCX: 00007f6c3e99c799 RDX: 000000000000001c RSI: 0000200000000240 RDI: 000000000000000e RBP: 00007f6c3ea32c99 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f6c3ec16038 R14: 00007f6c3ec15fa0 R15: 00007ffd9d146378 Allocated by task 6818: 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:5412 kmalloc_noprof include/linux/slab.h:950 [inline] kzalloc_noprof include/linux/slab.h:1188 [inline] ax25_dev_device_up+0x54/0x600 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:2289 [inline] call_netdevice_notifiers net/core/dev.c:2303 [inline] __dev_notify_flags+0x1a9/0x310 net/core/dev.c:9822 netif_change_flags+0xe8/0x1a0 net/core/dev.c:9851 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:1341 sock_ioctl+0x5c6/0x7f0 net/socket.c:1448 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+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 17444: 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] __rcu_free_sheaf_prepare+0x12d/0x2a0 mm/slub.c:2940 rcu_free_sheaf+0x31/0x200 mm/slub.c:5842 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:626 __do_softirq kernel/softirq.c:660 [inline] invoke_softirq kernel/softirq.c:496 [inline] __irq_exit_rcu+0xca/0x220 kernel/softirq.c:739 irq_exit_rcu+0x9/0x30 kernel/softirq.c:756 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 ffff888076670600 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 16 bytes inside of freed 256-byte region [ffff888076670600, ffff888076670700) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x76670 head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000040 ffff88801b041b40 dead000000000100 dead000000000122 raw: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000 head: 00fff00000000040 ffff88801b041b40 dead000000000100 dead000000000122 head: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000 head: 00fff00000000001 ffffffffffffff81 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 6077, tgid 6076 (syz.4.28), ts 93292734863, free_ts 88855408010 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x231/0x280 mm/page_alloc.c:1859 prep_new_page mm/page_alloc.c:1867 [inline] get_page_from_freelist+0x2418/0x24b0 mm/page_alloc.c:3926 __alloc_frozen_pages_noprof+0x233/0x3d0 mm/page_alloc.c:5213 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:7247 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:5291 [inline] __kmalloc_noprof+0x474/0x760 mm/slub.c:5304 kmalloc_noprof include/linux/slab.h:954 [inline] kzalloc_noprof include/linux/slab.h:1188 [inline] iter_file_splice_write+0x1da/0x10f0 fs/splice.c:678 do_splice_from fs/splice.c:936 [inline] direct_splice_actor+0x101/0x160 fs/splice.c:1159 splice_direct_to_actor+0x53a/0xc70 fs/splice.c:1103 do_splice_direct_actor fs/splice.c:1202 [inline] do_splice_direct+0x195/0x290 fs/splice.c:1228 do_sendfile+0x535/0x7d0 fs/read_write.c:1372 __do_sys_sendfile64 fs/read_write.c:1433 [inline] __se_sys_sendfile64+0x144/0x1a0 fs/read_write.c:1419 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f page last free pid 5997 tgid 5997 stack trace: create_dummy_stack mm/page_owner.c:103 [inline] register_dummy_stack+0x98/0x100 mm/page_owner.c:109 init_page_owner+0x2e/0x5f0 mm/page_owner.c:127 invoke_init_callbacks mm/page_ext.c:152 [inline] page_ext_init+0x500/0x540 mm/page_ext.c:490 mm_core_init+0x97/0xb0 mm/mm_init.c:2764 Memory state around the buggy address: ffff888076670500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888076670580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888076670600: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888076670680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888076670700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================