==================================================================
BUG: KASAN: slab-use-after-free in llc_conn_ac_send_sabme_cmd_p_set_x+0x442/0x470 net/llc/llc_c_ac.c:782
Read of size 1 at addr ffff888078b51010 by task syz.1.4125/21354
CPU: 0 UID: 0 PID: 21354 Comm: syz.1.4125 Tainted: G L syzkaller #0 PREEMPT(lazy)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Call Trace:
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0x13d/0x4b0 mm/kasan/report.c:482
kasan_report+0xdf/0x1c0 mm/kasan/report.c:595
llc_conn_ac_send_sabme_cmd_p_set_x+0x442/0x470 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+0x3ec/0x1480 net/llc/llc_conn.c:66
llc_process_tmr_ev net/llc/llc_c_ac.c:1442 [inline]
llc_conn_tmr_common_cb+0x2d4/0x880 net/llc/llc_c_ac.c:1325
call_timer_fn+0x19a/0x610 kernel/time/timer.c:1748
expire_timers kernel/time/timer.c:1799 [inline]
__run_timers+0x757/0xb00 kernel/time/timer.c:2374
__run_timer_base kernel/time/timer.c:2386 [inline]
__run_timer_base kernel/time/timer.c:2378 [inline]
run_timer_base+0x114/0x190 kernel/time/timer.c:2395
run_timer_softirq+0x1a/0x50 kernel/time/timer.c:2405
handle_softirqs+0x1ea/0x9b0 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0x162/0x210 kernel/softirq.c:735
irq_exit_rcu+0x9/0x30 kernel/softirq.c:752
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
sysvec_apic_timer_interrupt+0xa3/0xc0 arch/x86/kernel/apic/apic.c:1062
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:handle_mm_fault+0x3dc/0xa30 mm/memory.c:6700
Code: 20 31 ff 4c 89 fe e8 83 05 aa ff 4d 85 ff 74 08 e8 d9 0a aa ff 83 e5 fe e8 d1 0a aa ff 31 ff 44 89 f6 e8 37 05 aa ff 45 85 f6 <0f> 85 24 02 00 00 e8 b9 0a aa ff 41 89 ed 31 ff 41 81 e5 00 04 00
RSP: 0000:ffffc9000450fe40 EFLAGS: 00000202
RAX: 0000000000000002 RBX: ffff888028c01f00 RCX: ffffffff82604799
RDX: 0000000000000040 RSI: 0000000000000000 RDI: ffff888028c01f00
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000040 R11: 0000000000000000 R12: 0000000000001254
R13: 0000000000000000 R14: 0000000000000040 R15: 0000000000000000
do_user_addr_fault+0x5a3/0x12f0 arch/x86/mm/fault.c:1343
handle_page_fault arch/x86/mm/fault.c:1483 [inline]
exc_page_fault+0x6f/0xd0 arch/x86/mm/fault.c:1536
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595
RIP: 0033:0x7fcfc085524e
Code: c1 49 39 4f 08 72 54 8d 4d ff 85 ed 74 3b 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 39 f0 72 1b 4d 8b 07 49 89 c1 49 29 f1 <47> 0f b6 0c 08 45 84 c9 74 08 45 88 0c 00 49 8b 47 10 48 83 c0 01
RSP: 002b:00007fcfc1919470 EFLAGS: 00010206
RAX: 0000000000b6b001 RBX: 00007fcfc1919530 RCX: 000000000000000a
RDX: 0000000000000015 RSI: 0000000000000001 RDI: 00007fcfc19195d0
RBP: 0000000000000102 R08: 00007fcfb6600000 R09: 0000000000b6b000
R10: 0000000000000000 R11: 00007fcfc1919540 R12: 0000000000000001
R13: 00007fcfc0a54fa0 R14: 0000000000000000 R15: 00007fcfc19195d0
Allocated by task 21348:
kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
kasan_save_track+0x14/0x30 mm/kasan/common.c:78
poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
__kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:415
kasan_kmalloc include/linux/kasan.h:263 [inline]
__kmalloc_cache_noprof+0x2e5/0x6c0 mm/slub.c:5489
_kmalloc_noprof include/linux/slab.h:988 [inline]
_kzalloc_noprof include/linux/slab.h:1309 [inline]
llc_sap_alloc net/llc/llc_core.c:29 [inline]
llc_sap_open+0x120/0x3b0 net/llc/llc_core.c:96
llc_ui_autobind.isra.0+0x2ae/0x580 net/llc/af_llc.c:301
llc_ui_connect+0x582/0xdb0 net/llc/af_llc.c:498
__sys_connect_file+0x141/0x1a0 net/socket.c:2135
__sys_connect+0x141/0x170 net/socket.c:2154
__do_sys_connect net/socket.c:2160 [inline]
__se_sys_connect net/socket.c:2157 [inline]
__x64_sys_connect+0x72/0xb0 net/socket.c:2157
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 14820:
kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
kasan_save_track+0x14/0x30 mm/kasan/common.c:78
kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584
poison_slab_object mm/kasan/common.c:253 [inline]
__kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285
kasan_slab_free include/linux/kasan.h:235 [inline]
slab_free_hook mm/slub.c:2677 [inline]
__rcu_free_sheaf_prepare+0x5d/0x2f0 mm/slub.c:2928
rcu_free_sheaf+0x1a/0xe0 mm/slub.c:5978
rcu_do_batch kernel/rcu/tree.c:2645 [inline]
rcu_core+0x5a2/0x10d0 kernel/rcu/tree.c:2897
handle_softirqs+0x1ea/0x9b0 kernel/softirq.c:622
do_softirq kernel/softirq.c:523 [inline]
do_softirq+0xac/0xe0 kernel/softirq.c:510
__local_bh_enable_ip+0xf8/0x120 kernel/softirq.c:450
spin_unlock_bh include/linux/spinlock.h:396 [inline]
bond_3ad_state_machine_handler+0xcfd/0x5e20 drivers/net/bonding/bond_3ad.c:2618
process_one_work+0xa23/0x1940 kernel/workqueue.c:3322
process_scheduled_works kernel/workqueue.c:3405 [inline]
worker_thread+0x5ef/0xe50 kernel/workqueue.c:3486
kthread+0x370/0x450 kernel/kthread.c:436
ret_from_fork+0x72b/0xd50 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 ffff888078b51000
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 16 bytes inside of
freed 2048-byte region [ffff888078b51000, ffff888078b51800)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x78b50
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 ffff88813fe24000 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800080008 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88813fe24000 dead000000000100 dead000000000122
head: 0000000000000000 0000000800080008 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 5608, tgid 5608 (syz-executor), ts 97575291125, free_ts 59415464319
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1859
prep_new_page mm/page_alloc.c:1867 [inline]
get_page_from_freelist+0xf48/0x3530 mm/page_alloc.c:3946
__alloc_frozen_pages_noprof+0x299/0x2dc0 mm/page_alloc.c:5304
alloc_slab_page mm/slub.c:3266 [inline]
allocate_slab mm/slub.c:3380 [inline]
new_slab+0xa2/0x640 mm/slub.c:3426
refill_objects+0xe3/0x410 mm/slub.c:7310
refill_sheaf mm/slub.c:2804 [inline]
__pcs_replace_empty_main+0x376/0x680 mm/slub.c:4675
alloc_from_pcs mm/slub.c:4773 [inline]
slab_alloc_node mm/slub.c:4905 [inline]
__do_kmalloc_node mm/slub.c:5333 [inline]
__kmalloc_node_track_caller_noprof+0x679/0x830 mm/slub.c:5471
kmalloc_reserve+0xe8/0x350 net/core/skbuff.c:637
pskb_expand_head+0x249/0x10e0 net/core/skbuff.c:2312
netlink_trim+0x22d/0x2f0 net/netlink/af_netlink.c:1300
netlink_broadcast_filtered+0x6d/0xf20 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+0xb1/0x290 net/netlink/af_netlink.c:2599
rtnl_notify net/core/rtnetlink.c:963 [inline]
rtmsg_ifinfo_send net/core/rtnetlink.c:4553 [inline]
rtmsg_ifinfo_event net/core/rtnetlink.c:4569 [inline]
rtmsg_ifinfo_event net/core/rtnetlink.c:4556 [inline]
rtmsg_ifinfo+0x177/0x1b0 net/core/rtnetlink.c:4575
__dev_notify_flags+0x24c/0x2e0 net/core/dev.c:9795
rtnl_configure_link+0x1b5/0x280 net/core/rtnetlink.c:3679
rtnl_newlink_create net/core/rtnetlink.c:3923 [inline]
__rtnl_newlink net/core/rtnetlink.c:4044 [inline]
rtnl_newlink+0x153b/0x2380 net/core/rtnetlink.c:4159
page last free pid 5302 tgid 5302 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
__free_pages_prepare mm/page_alloc.c:1406 [inline]
__free_frozen_pages+0x79f/0x1090 mm/page_alloc.c:2950
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x47/0xf0 mm/kasan/quarantine.c:179
kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286
__kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:350
kasan_slab_alloc include/linux/kasan.h:253 [inline]
slab_post_alloc_hook mm/slub.c:4584 [inline]
slab_alloc_node mm/slub.c:4917 [inline]
kmem_cache_alloc_noprof+0x26b/0x6a0 mm/slub.c:4931
mt_alloc_one lib/maple_tree.c:139 [inline]
mas_alloc_nodes lib/maple_tree.c:1089 [inline]
mas_preallocate+0x1105/0x14a0 lib/maple_tree.c:4961
vma_iter_prealloc mm/vma.h:577 [inline]
commit_merge+0x3e3/0xbd0 mm/vma.c:754
vma_expand+0xac5/0xea0 mm/vma.c:1219
vma_merge_new_range+0x516/0xc00 mm/vma.c:1112
__mmap_region+0xa86/0x2db0 mm/vma.c:2769
mmap_region+0x35d/0x620 mm/vma.c:2860
do_mmap+0xc63/0x12f0 mm/mmap.c:560
vm_mmap_pgoff+0x29e/0x470 mm/util.c:581
ksys_mmap_pgoff+0x3cb/0x610 mm/mmap.c:606
__do_sys_mmap arch/x86/kernel/sys_x86_64.c:89 [inline]
__se_sys_mmap arch/x86/kernel/sys_x86_64.c:82 [inline]
__x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:82
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
Memory state around the buggy address:
ffff888078b50f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888078b50f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888078b51000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888078b51080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888078b51100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess):
0: 20 31 and %dh,(%rcx)
2: ff 4c 89 fe decl -0x2(%rcx,%rcx,4)
6: e8 83 05 aa ff call 0xffaa058e
b: 4d 85 ff test %r15,%r15
e: 74 08 je 0x18
10: e8 d9 0a aa ff call 0xffaa0aee
15: 83 e5 fe and $0xfffffffe,%ebp
18: e8 d1 0a aa ff call 0xffaa0aee
1d: 31 ff xor %edi,%edi
1f: 44 89 f6 mov %r14d,%esi
22: e8 37 05 aa ff call 0xffaa055e
27: 45 85 f6 test %r14d,%r14d
* 2a: 0f 85 24 02 00 00 jne 0x254 <-- trapping instruction
30: e8 b9 0a aa ff call 0xffaa0aee
35: 41 89 ed mov %ebp,%r13d
38: 31 ff xor %edi,%edi
3a: 41 rex.B
3b: 81 .byte 0x81
3c: e5 00 in $0x0,%eax
3e: 04 00 add $0x0,%al