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KASAN: slab-use-after-free Read in ax25_send_frame

Status: auto-obsoleted due to no activity on 2025/12/31 09:06
Subsystems: hams
[Documentation on labels]
First crash: 159d, last: 159d
▶ ▼ Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: slab-use-after-free Read in ax25_send_frame (2) hams 19 7 5d20h 44d 0/29 closed as invalid on 2026/03/27 01:43
upstream general protection fault in ax25_send_frame (2) hams 10 13 1241d 1228d 22/29 fixed on 2023/02/24 13:50

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in ax25_send_frame+0x67c/0x9f0 net/ax25/ax25_out.c:75
Read of size 7 at addr ffff888056c43c08 by task swapper/0/0

CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <IRQ>
 dump_stack_lvl+0x189/0x250 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
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x2b0/0x2c0 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+0x111/0x220 net/rose/rose_link.c:106
 rose_transmit_restart_request net/rose/rose_link.c:198 [inline]
 rose_t0timer_expiry+0x143/0x350 net/rose/rose_link.c:83
 call_timer_fn+0x17e/0x5f0 kernel/time/timer.c:1747
 expire_timers kernel/time/timer.c:1798 [inline]
 __run_timers kernel/time/timer.c:2372 [inline]
 __run_timer_base+0x61a/0x860 kernel/time/timer.c:2384
 run_timer_base kernel/time/timer.c:2393 [inline]
 run_timer_softirq+0xb7/0x180 kernel/time/timer.c:2403
 handle_softirqs+0x286/0x870 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:723
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:739
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline]
 sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1052
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:82
Code: cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d b3 98 1f 00 f3 0f 1e fa fb f4 <e9> c8 e7 02 00 cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffffff8dc07d80 EFLAGS: 000002c6
RAX: 8dc4ea12cc8e1b00 RBX: ffffffff8196ac67 RCX: 8dc4ea12cc8e1b00
RDX: 0000000000000001 RSI: ffffffff8d750441 RDI: ffffffff8bbf17e0
RBP: ffffffff8dc07ea8 R08: ffff8880b8632fdb R09: 1ffff110170c65fb
R10: dffffc0000000000 R11: ffffed10170c65fc R12: ffffffff8f7d3f70
R13: 0000000000000000 R14: 0000000000000000 R15: 1ffffffff1b92a40
 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:767
 default_idle_call+0x73/0xb0 kernel/sched/idle.c:122
 cpuidle_idle_call kernel/sched/idle.c:190 [inline]
 do_idle+0x1e7/0x510 kernel/sched/idle.c:330
 cpu_startup_entry+0x44/0x60 kernel/sched/idle.c:428
 rest_init+0x2de/0x300 init/main.c:757
 start_kernel+0x3ae/0x410 init/main.c:1111
 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310
 x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:291
 common_startup_64+0x13e/0x147
 </TASK>

Allocated by task 18879:
 kasan_save_stack mm/kasan/common.c:56 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:77
 poison_kmalloc_redzone mm/kasan/common.c:397 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:414
 kasan_kmalloc include/linux/kasan.h:262 [inline]
 __kmalloc_cache_noprof+0x3e2/0x700 mm/slub.c:5755
 kmalloc_noprof include/linux/slab.h:957 [inline]
 rose_add_node+0x23a/0xeb0 net/rose/rose_route.c:85
 rose_rt_ioctl+0xce2/0x1240 net/rose/rose_route.c:748
 rose_ioctl+0x3ce/0x8b0 net/rose/af_rose.c:1381
 sock_do_ioctl+0xdc/0x300 net/socket.c:1254
 sock_ioctl+0x576/0x790 net/socket.c:1375
 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+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 21673:
 kasan_save_stack mm/kasan/common.c:56 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:77
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:252 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:284
 kasan_slab_free include/linux/kasan.h:234 [inline]
 slab_free_hook mm/slub.c:2530 [inline]
 slab_free mm/slub.c:6619 [inline]
 kfree+0x19a/0x6d0 mm/slub.c:6826
 rose_neigh_put include/net/rose.h:166 [inline]
 rose_timer_expiry+0x4cb/0x600 net/rose/rose_timer.c:183
 call_timer_fn+0x17e/0x5f0 kernel/time/timer.c:1747
 expire_timers kernel/time/timer.c:1798 [inline]
 __run_timers kernel/time/timer.c:2372 [inline]
 __run_timer_base+0x61a/0x860 kernel/time/timer.c:2384
 run_timer_base kernel/time/timer.c:2393 [inline]
 run_timer_softirq+0xb7/0x180 kernel/time/timer.c:2403
 handle_softirqs+0x286/0x870 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:723
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:739
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline]
 sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1052
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697

The buggy address belongs to the object at ffff888056c43c00
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 8 bytes inside of
 freed 512-byte region [ffff888056c43c00, ffff888056c43e00)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x56c40
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
anon flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88813ff26c80 0000000000000000 dead000000000001
raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88813ff26c80 0000000000000000 dead000000000001
head: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000002 ffffea00015b1001 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 0x52820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 5838, tgid 5838 (syz-executor), ts 76683420493, free_ts 22791050371
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x2365/0x2440 mm/page_alloc.c:3920
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5214
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2418
 alloc_slab_page mm/slub.c:3046 [inline]
 allocate_slab+0x96/0x3a0 mm/slub.c:3219
 new_slab mm/slub.c:3273 [inline]
 ___slab_alloc+0xe94/0x18a0 mm/slub.c:4643
 __slab_alloc+0x65/0x100 mm/slub.c:4762
 __slab_alloc_node mm/slub.c:4838 [inline]
 slab_alloc_node mm/slub.c:5260 [inline]
 __do_kmalloc_node mm/slub.c:5633 [inline]
 __kmalloc_noprof+0x47d/0x800 mm/slub.c:5646
 kmalloc_noprof include/linux/slab.h:961 [inline]
 kzalloc_noprof include/linux/slab.h:1094 [inline]
 fib6_info_alloc+0x30/0xf0 net/ipv6/ip6_fib.c:155
 ip6_route_info_create+0x142/0x860 net/ipv6/route.c:3809
 addrconf_f6i_alloc+0x1d2/0x450 net/ipv6/route.c:4678
 fixup_permanent_addr net/ipv6/addrconf.c:3583 [inline]
 addrconf_permanent_addr+0x274/0x9d0 net/ipv6/addrconf.c:3622
 addrconf_notify+0x887/0x1010 net/ipv6/addrconf.c:3694
 notifier_call_chain+0x1b6/0x3e0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2267 [inline]
 call_netdevice_notifiers net/core/dev.c:2281 [inline]
 __dev_notify_flags+0x18d/0x2e0 net/core/dev.c:-1
 netif_change_flags+0xe8/0x1a0 net/core/dev.c:9745
page last free pid 1 tgid 1 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 __free_frozen_pages+0xbc8/0xd30 mm/page_alloc.c:2948
 __free_pages mm/page_alloc.c:5333 [inline]
 free_contig_range+0x1bd/0x4a0 mm/page_alloc.c:7176
 destroy_args+0x69/0x660 mm/debug_vm_pgtable.c:958
 debug_vm_pgtable+0x39f/0x3b0 mm/debug_vm_pgtable.c:1345
 do_one_initcall+0x236/0x820 init/main.c:1283
 do_initcall_level+0x104/0x190 init/main.c:1345
 do_initcalls+0x59/0xa0 init/main.c:1361
 kernel_init_freeable+0x334/0x4b0 init/main.c:1593
 kernel_init+0x1d/0x1d0 init/main.c:1483
 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff888056c43b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888056c43b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888056c43c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff888056c43c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888056c43d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess):
   0:	cc                   	int3
   1:	cc                   	int3
   2:	cc                   	int3
   3:	cc                   	int3
   4:	cc                   	int3
   5:	cc                   	int3
   6:	cc                   	int3
   7:	90                   	nop
   8:	90                   	nop
   9:	90                   	nop
   a:	90                   	nop
   b:	90                   	nop
   c:	90                   	nop
   d:	90                   	nop
   e:	90                   	nop
   f:	90                   	nop
  10:	90                   	nop
  11:	90                   	nop
  12:	90                   	nop
  13:	90                   	nop
  14:	90                   	nop
  15:	90                   	nop
  16:	90                   	nop
  17:	f3 0f 1e fa          	endbr64
  1b:	66 90                	xchg   %ax,%ax
  1d:	0f 00 2d b3 98 1f 00 	verw   0x1f98b3(%rip)        # 0x1f98d7
  24:	f3 0f 1e fa          	endbr64
  28:	fb                   	sti
  29:	f4                   	hlt
* 2a:	e9 c8 e7 02 00       	jmp    0x2e7f7 <-- trapping instruction
  2f:	cc                   	int3
  30:	cc                   	int3
  31:	cc                   	int3
  32:	cc                   	int3
  33:	cc                   	int3
  34:	cc                   	int3
  35:	cc                   	int3
  36:	cc                   	int3
  37:	90                   	nop
  38:	90                   	nop
  39:	90                   	nop
  3a:	90                   	nop
  3b:	90                   	nop
  3c:	90                   	nop
  3d:	90                   	nop
  3e:	90                   	nop
  3f:	90                   	nop

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/10/22 08:43 linux-next fe45352cd106 252fbbad .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: slab-use-after-free Read in ax25_send_frame
* Struck through repros no longer work on HEAD.