==================================================================
BUG: KASAN: slab-use-after-free in llc_conn_ac_send_sabme_cmd_p_set_x+0x38a/0x420 net/llc/llc_c_ac.c:782
Read of size 1 at addr ffff888033d3b010 by task syz.1.6158/4886
CPU: 1 UID: 0 PID: 4886 Comm: syz.1.6158 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
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
llc_conn_ac_send_sabme_cmd_p_set_x+0x38a/0x420 net/llc/llc_c_ac.c:782
llc_exec_conn_trans_actions net/llc/llc_conn.c:437 [inline]
llc_conn_service net/llc/llc_conn.c:362 [inline]
llc_conn_state_process+0x4fb/0x1380 net/llc/llc_conn.c:66
llc_process_tmr_ev net/llc/llc_c_ac.c:1442 [inline]
llc_conn_tmr_common_cb+0x34a/0x780 net/llc/llc_c_ac.c:1325
call_timer_fn+0x18d/0x5f0 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+0x226/0x860 kernel/softirq.c:645
__do_softirq kernel/softirq.c:679 [inline]
invoke_softirq kernel/softirq.c:519 [inline]
__irq_exit_rcu+0xcb/0x220 kernel/softirq.c:758
irq_exit_rcu+0x9/0x30 kernel/softirq.c:775
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1062
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:26 [inline]
RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:109 [inline]
RIP: 0010:arch_local_irq_save arch/x86/include/asm/irqflags.h:127 [inline]
RIP: 0010:lock_acquire+0xb7/0x350 kernel/locking/lockdep.c:5938
Code: 67 0b f2 11 85 c0 0f 85 d5 00 00 00 65 48 8b 2d a7 c6 f1 11 83 bd a4 0b 00 00 00 0f 85 c0 00 00 00 48 89 5c 24 08 4c 89 fb 9c <41> 5f fa 48 c7 c7 29 23 49 8e e8 aa 39 42 0a 65 ff 05 2b 0b f2 11
RSP: 0018:ffffc900063f7460 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000001 RCX: 8000000000000001
RDX: 0000000000000000 RSI: ffffffff82295ff1 RDI: 1ffffffff1dd201c
RBP: ffff88802cd8be80 R08: 0000000000000001 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff20f4650 R12: ffffffff8ee900e0
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000001
__fs_reclaim_acquire mm/page_alloc.c:4375 [inline]
fs_reclaim_acquire+0x71/0x100 mm/page_alloc.c:4389
might_alloc include/linux/sched/mm.h:316 [inline]
slab_pre_alloc_hook mm/slub.c:4636 [inline]
slab_alloc_node mm/slub.c:4974 [inline]
kmem_cache_alloc_node_noprof+0x5f/0x610 mm/slub.c:5068
__alloc_skb+0x1db/0x7a0 net/core/skbuff.c:704
alloc_skb include/linux/skbuff.h:1384 [inline]
nlmsg_new include/net/netlink.h:1055 [inline]
netlink_ack+0x136/0xb30 net/netlink/af_netlink.c:2493
netlink_rcv_skb+0x2a4/0x4a0 net/netlink/af_netlink.c:2562
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
netlink_unicast+0x7bd/0x940 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1900
sock_sendmsg_nosec+0x13a/0x180 net/socket.c:800
__sock_sendmsg net/socket.c:815 [inline]
____sys_sendmsg+0x54e/0x850 net/socket.c:2712
___sys_sendmsg+0x2a5/0x360 net/socket.c:2766
__sys_sendmsg net/socket.c:2798 [inline]
__do_sys_sendmsg net/socket.c:2803 [inline]
__se_sys_sendmsg net/socket.c:2801 [inline]
__x64_sys_sendmsg+0x1b1/0x290 net/socket.c:2801
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f88d5b9e159
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:00007f88d6ab7028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f88d5e26270 RCX: 00007f88d5b9e159
RDX: 0000000000000000 RSI: 0000200000000240 RDI: 0000000000000008
RBP: 00007f88d5c3506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f88d5e26308 R14: 00007f88d5e26270 R15: 00007ffc562d9bd8
Allocated by task 4863:
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+0x321/0x600 mm/slub.c:5563
_kmalloc_noprof include/linux/slab.h:991 [inline]
_kzalloc_noprof include/linux/slab.h:1312 [inline]
llc_sap_alloc net/llc/llc_core.c:29 [inline]
llc_sap_open+0xe1/0x3b0 net/llc/llc_core.c:96
llc_ui_autobind+0x1f1/0x560 net/llc/af_llc.c:301
llc_ui_connect+0x1d7/0xd50 net/llc/af_llc.c:498
connect_socket net/socket.c:2140 [inline]
__sys_connect_file net/socket.c:2165 [inline]
__sys_connect+0x316/0x450 net/socket.c:2182
__do_sys_connect net/socket.c:2188 [inline]
__se_sys_connect net/socket.c:2185 [inline]
__x64_sys_connect+0x7a/0x90 net/socket.c:2185
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 24:
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
kasan_save_free_info+0x40/0x50 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:2748 [inline]
__rcu_free_sheaf_prepare+0x12d/0x2a0 mm/slub.c:3009
rcu_free_sheaf+0x31/0x200 mm/slub.c:6052
rcu_do_batch kernel/rcu/tree.c:2650 [inline]
rcu_core+0x926/0x1260 kernel/rcu/tree.c:2919
handle_softirqs+0x226/0x860 kernel/softirq.c:645
run_ksoftirqd+0x36/0x60 kernel/softirq.c:1099
smpboot_thread_fn+0x565/0xa70 kernel/smpboot.c:160
kthread+0x38b/0x480 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 ffff888033d3b000
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 16 bytes inside of
freed 2048-byte region [ffff888033d3b000, ffff888033d3b800)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x33d38
head: order:3 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 ffff88801b042000 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000080008 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801b042000 dead000000000100 dead000000000122
head: 0000000000000000 0000000000080008 00000000f5000000 0000000000000000
head: 00fff00000000003 fffffffffffffe01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd2820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5613, tgid 5613 (syz-executor), ts 89165458130
set_page_owner include/linux/page_owner.h:33 [inline]
post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1871
prep_new_page mm/page_alloc.c:1879 [inline]
get_page_from_freelist+0x2209/0x2280 mm/page_alloc.c:3943
__alloc_frozen_pages_noprof+0x217/0x5a0 mm/page_alloc.c:5436
alloc_slab_page mm/slub.c:3347 [inline]
allocate_slab+0x7d/0x620 mm/slub.c:3462
new_slab mm/slub.c:3513 [inline]
refill_objects+0x2d5/0x350 mm/slub.c:7410
refill_sheaf mm/slub.c:2885 [inline]
__pcs_replace_empty_main+0x2c8/0x6c0 mm/slub.c:4774
alloc_from_pcs mm/slub.c:4850 [inline]
slab_alloc_node mm/slub.c:4984 [inline]
__do_kmalloc_node mm/slub.c:5413 [inline]
__kmalloc_node_track_caller_noprof+0x548/0x720 mm/slub.c:5545
kmalloc_reserve net/core/skbuff.c:637 [inline]
pskb_expand_head+0x22c/0x13a0 net/core/skbuff.c:2315
netlink_trim+0x1b3/0x2c0 net/netlink/af_netlink.c:1300
netlink_broadcast_filtered+0x6d/0xea0 net/netlink/af_netlink.c:1518
nlmsg_multicast_filtered include/net/netlink.h:1165 [inline]
nlmsg_multicast include/net/netlink.h:1184 [inline]
nlmsg_notify+0xe3/0x1a0 net/netlink/af_netlink.c:2599
__dev_notify_flags+0x257/0x510 net/core/dev.c:9849
rtnl_configure_link+0x2f5/0x510 net/core/rtnetlink.c:3759
vxcan_newlink+0x3ee/0x720 drivers/net/can/vxcan.c:253
rtnl_newlink_create+0x305/0x7b0 net/core/rtnetlink.c:3996
__rtnl_newlink net/core/rtnetlink.c:4125 [inline]
rtnl_newlink+0x167a/0x1c30 net/core/rtnetlink.c:4242
page last free pid 5641 tgid 5641 ts 87605538509 stack trace:
reset_page_owner include/linux/page_owner.h:26 [inline]
__free_pages_prepare mm/page_alloc.c:1418 [inline]
__free_frozen_pages+0xc93/0xd90 mm/page_alloc.c:2962
__slab_free+0x274/0x2c0 mm/slub.c:5815
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179
kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
__kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
kasan_slab_alloc include/linux/kasan.h:253 [inline]
slab_post_alloc_hook mm/slub.c:4683 [inline]
slab_alloc_node mm/slub.c:4996 [inline]
__do_kmalloc_node mm/slub.c:5413 [inline]
__kmalloc_noprof+0x307/0x720 mm/slub.c:5439
_kmalloc_noprof include/linux/slab.h:995 [inline]
load_elf_phdrs fs/binfmt_elf.c:537 [inline]
load_elf_binary+0x2c6/0x28d0 fs/binfmt_elf.c:866
search_binary_handler fs/exec.c:1765 [inline]
exec_binprm fs/exec.c:1797 [inline]
bprm_execve+0x930/0x1590 fs/exec.c:1853
kernel_execve+0x8c3/0x9c0 fs/exec.c:1997
call_usermodehelper_exec_async+0x20f/0x360 kernel/umh.c:107
ret_from_fork+0x514/0xb70 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:
ffff888033d3af00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888033d3af80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888033d3b000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888033d3b080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888033d3b100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess):
0: 67 0b f2 addr32 or %edx,%esi
3: 11 85 c0 0f 85 d5 adc %eax,-0x2a7af040(%rbp)
9: 00 00 add %al,(%rax)
b: 00 65 48 add %ah,0x48(%rbp)
e: 8b 2d a7 c6 f1 11 mov 0x11f1c6a7(%rip),%ebp # 0x11f1c6bb
14: 83 bd a4 0b 00 00 00 cmpl $0x0,0xba4(%rbp)
1b: 0f 85 c0 00 00 00 jne 0xe1
21: 48 89 5c 24 08 mov %rbx,0x8(%rsp)
26: 4c 89 fb mov %r15,%rbx
29: 9c pushf
* 2a: 41 5f pop %r15 <-- trapping instruction
2c: fa cli
2d: 48 c7 c7 29 23 49 8e mov $0xffffffff8e492329,%rdi
34: e8 aa 39 42 0a call 0xa4239e3
39: 65 ff 05 2b 0b f2 11 incl %gs:0x11f20b2b(%rip) # 0x11f20b6b