KASAN: use-after-free Read in tipc_skb_dump

Status: upstream: reported C repro on 2026/09/10 07:21
Reported-by: syzbot+73fc8d119af8a272d18a@syzkaller.appspotmail.com
First crash: 40d, last: 18d
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2026/09/20 lts (merge base) [unknown] C Failed due to an error; will retry later
2026/09/20 upstream (ToT) [unknown] C Failed due to an error; will retry later
▶ ▼ Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-6-12 KASAN: slab-use-after-free Read in tipc_skb_dump 19 3 3d03h 52d 0/1 premoderation: reported on 2026/08/06 18:51
▶ ▼ Last patch testing requests (1)
Created Duration User Patch Repo Result
2026/09/27 17:30 14m retest repro android13-5.15-lts no crash job log log

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in msg_word net/tipc/msg.h:207 [inline]
BUG: KASAN: use-after-free in msg_bits net/tipc/msg.h:217 [inline]
BUG: KASAN: use-after-free in msg_hdr_sz net/tipc/msg.h:267 [inline]
BUG: KASAN: use-after-free in msg_short net/tipc/msg.h:634 [inline]
BUG: KASAN: use-after-free in msg_orignode net/tipc/msg.h:639 [inline]
BUG: KASAN: use-after-free in tipc_skb_dump+0x10ff/0x1780 net/tipc/trace.c:73
Read of size 4 at addr ffff8881124a70b0 by task syz.2.30/414

CPU: 0 PID: 414 Comm: syz.2.30 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:88
 dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106
 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:427 [inline]
 kasan_report+0x10f/0x150 mm/kasan/report.c:444
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308
 msg_word net/tipc/msg.h:207 [inline]
 msg_bits net/tipc/msg.h:217 [inline]
 msg_hdr_sz net/tipc/msg.h:267 [inline]
 msg_short net/tipc/msg.h:634 [inline]
 msg_orignode net/tipc/msg.h:639 [inline]
 tipc_skb_dump+0x10ff/0x1780 net/tipc/trace.c:73
 tipc_list_dump+0x22b/0x2f0 net/tipc/trace.c:187
 tipc_sk_dump+0xa12/0xfb0 net/tipc/socket.c:4008
 perf_trace_tipc_sk_class+0x3cc/0x5e0 net/tipc/trace.h:205
 trace_tipc_sk_rej_msg net/tipc/trace.h:230 [inline]
 tipc_sk_enqueue net/tipc/socket.c:2470 [inline]
 tipc_sk_rcv+0x292e/0x2ca0 net/tipc/socket.c:2502
 tipc_node_xmit+0x36f/0xd80 net/tipc/node.c:1703
 __tipc_sendstream+0xa6e/0x1190 net/tipc/socket.c:1629
 tipc_sendstream+0x55/0x70 net/tipc/socket.c:1553
 sock_sendmsg_nosec net/socket.c:704 [inline]
 __sock_sendmsg net/socket.c:716 [inline]
 ____sys_sendmsg+0x5be/0x8f0 net/socket.c:2436
 ___sys_sendmsg+0x236/0x2e0 net/socket.c:2490
 __sys_sendmsg net/socket.c:2519 [inline]
 __do_sys_sendmsg net/socket.c:2528 [inline]
 __se_sys_sendmsg net/socket.c:2526 [inline]
 __x64_sys_sendmsg+0x201/0x2d0 net/socket.c:2526
 x64_sys_call+0x4b/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:47
 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: 0033:0x7fc068302159
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:00007fc068163028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fc068589fa0 RCX: 00007fc068302159
RDX: 0000000000000001 RSI: 0000200000000240 RDI: 0000000000000005
RBP: 00007fc06839903b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc06858a038 R14: 00007fc068589fa0 R15: 00007fff6dc443a8
 </TASK>

Allocated by task 414:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:45 [inline]
 set_alloc_info mm/kasan/common.c:433 [inline]
 ____kasan_kmalloc mm/kasan/common.c:512 [inline]
 __kasan_kmalloc+0xd4/0x100 mm/kasan/common.c:521
 kasan_kmalloc include/linux/kasan.h:227 [inline]
 __kmalloc_track_caller+0x13c/0x2c0 mm/slub.c:4959
 kmalloc_reserve net/core/skbuff.c:357 [inline]
 __alloc_skb+0x210/0x730 net/core/skbuff.c:428
 alloc_skb_fclone include/linux/skbuff.h:1233 [inline]
 tipc_buf_acquire net/tipc/msg.c:72 [inline]
 tipc_msg_build+0xce/0xf30 net/tipc/msg.c:402
 __tipc_sendstream+0x8f3/0x1190 net/tipc/socket.c:1622
 tipc_sendstream+0x55/0x70 net/tipc/socket.c:1553
 sock_sendmsg_nosec net/socket.c:704 [inline]
 __sock_sendmsg net/socket.c:716 [inline]
 ____sys_sendmsg+0x5be/0x8f0 net/socket.c:2436
 ___sys_sendmsg+0x236/0x2e0 net/socket.c:2490
 __sys_sendmsg net/socket.c:2519 [inline]
 __do_sys_sendmsg net/socket.c:2528 [inline]
 __se_sys_sendmsg net/socket.c:2526 [inline]
 __x64_sys_sendmsg+0x201/0x2d0 net/socket.c:2526
 x64_sys_call+0x4b/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:47
 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 415:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4a/0x70 mm/kasan/common.c:45
 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370
 ____kasan_slab_free+0x125/0x160 mm/kasan/common.c:365
 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:373
 kasan_slab_free include/linux/kasan.h:193 [inline]
 slab_free_hook mm/slub.c:1728 [inline]
 slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1754
 slab_free mm/slub.c:3526 [inline]
 kfree+0xc4/0x270 mm/slub.c:4588
 skb_free_head net/core/skbuff.c:656 [inline]
 skb_release_data+0x7bd/0xa20 net/core/skbuff.c:678
 skb_release_all net/core/skbuff.c:743 [inline]
 __kfree_skb net/core/skbuff.c:757 [inline]
 kfree_skb_reason net/core/skbuff.c:778 [inline]
 kfree_skb+0xb9/0x2f0 net/core/skbuff.c:792
 tsk_advance_rx_queue+0x10f/0x240 net/tipc/socket.c:281
 tipc_recvstream+0x881/0xe70 net/tipc/socket.c:2057
 ____sys_recvmsg+0x2ca/0x5b0 net/socket.c:-1
 ___sys_recvmsg+0x213/0x5c0 net/socket.c:2697
 __sys_recvmsg net/socket.c:2727 [inline]
 __do_sys_recvmsg net/socket.c:2737 [inline]
 __se_sys_recvmsg net/socket.c:2734 [inline]
 __x64_sys_recvmsg+0x1fe/0x2d0 net/socket.c:2734
 x64_sys_call+0x705/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:48
 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

The buggy address belongs to the object at ffff8881124a7000
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 176 bytes inside of
 1024-byte region [ffff8881124a7000, ffff8881124a7400)
The buggy address belongs to the page:
page:ffffea0004492800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1124a0
head:ffffea0004492800 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head|zone=1)
raw: 4000000000010200 0000000000000000 dead000000000122 ffff888100043080
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 414, ts 26288721626, free_ts 26265052788
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x192/0x1b0 mm/page_alloc.c:2607
 prep_new_page+0x1c/0x110 mm/page_alloc.c:2613
 get_page_from_freelist+0x2c3a/0x2cd0 mm/page_alloc.c:4487
 __alloc_pages+0x1a2/0x460 mm/page_alloc.c:5824
 alloc_slab_page mm/slub.c:-1 [inline]
 allocate_slab mm/slub.c:1937 [inline]
 new_slab+0xa0/0x4d0 mm/slub.c:2000
 ___slab_alloc+0x3ac/0x840 mm/slub.c:3033
 __slab_alloc+0x49/0x90 mm/slub.c:3120
 slab_alloc_node mm/slub.c:3211 [inline]
 slab_alloc mm/slub.c:3255 [inline]
 __kmalloc_track_caller+0x169/0x2c0 mm/slub.c:4954
 kmalloc_reserve net/core/skbuff.c:357 [inline]
 __alloc_skb+0x210/0x730 net/core/skbuff.c:428
 alloc_skb_fclone include/linux/skbuff.h:1233 [inline]
 tipc_buf_acquire net/tipc/msg.c:72 [inline]
 tipc_msg_build+0xce/0xf30 net/tipc/msg.c:402
 __tipc_sendstream+0x8f3/0x1190 net/tipc/socket.c:1622
 tipc_sendstream+0x55/0x70 net/tipc/socket.c:1553
 sock_sendmsg_nosec net/socket.c:704 [inline]
 __sock_sendmsg net/socket.c:716 [inline]
 ____sys_sendmsg+0x5be/0x8f0 net/socket.c:2436
 ___sys_sendmsg+0x236/0x2e0 net/socket.c:2490
 __sys_sendmsg net/socket.c:2519 [inline]
 __do_sys_sendmsg net/socket.c:2528 [inline]
 __se_sys_sendmsg net/socket.c:2526 [inline]
 __x64_sys_sendmsg+0x201/0x2d0 net/socket.c:2526
 x64_sys_call+0x4b/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:47
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 free_pages_prepare mm/page_alloc.c:1474 [inline]
 free_pcp_prepare mm/page_alloc.c:1546 [inline]
 free_unref_page_prepare+0x5fa/0x600 mm/page_alloc.c:3536
 free_unref_page+0xae/0x540 mm/page_alloc.c:3618
 free_the_page mm/page_alloc.c:805 [inline]
 __free_pages+0x6c/0x100 mm/page_alloc.c:5900
 __free_slab+0xe5/0x1e0 mm/slub.c:2025
 free_slab mm/slub.c:2040 [inline]
 discard_slab mm/slub.c:2046 [inline]
 __unfreeze_partials+0x15a/0x190 mm/slub.c:2532
 put_cpu_partial+0xc6/0x120 mm/slub.c:2612
 __slab_free+0x1d4/0x290 mm/slub.c:3395
 do_slab_free mm/slub.c:3514 [inline]
 ___cache_free+0x104/0x120 mm/slub.c:3535
 qlink_free+0x4d/0x90 mm/kasan/quarantine.c:157
 qlist_free_all+0x5f/0xb0 mm/kasan/quarantine.c:176
 kasan_quarantine_reduce+0x14a/0x170 mm/kasan/quarantine.c:283
 __kasan_slab_alloc+0x2f/0xe0 mm/kasan/common.c:443
 kasan_slab_alloc include/linux/kasan.h:217 [inline]
 slab_post_alloc_hook+0x4f/0x2b0 mm/slab.h:550
 slab_alloc_node mm/slub.c:3245 [inline]
 slab_alloc mm/slub.c:3255 [inline]
 kmem_cache_alloc+0xf7/0x260 mm/slub.c:3260
 kmem_cache_alloc_node include/linux/slab.h:492 [inline]
 __alloc_skb+0xe4/0x730 net/core/skbuff.c:416
 alloc_skb include/linux/skbuff.h:1183 [inline]
 netlink_alloc_large_skb net/netlink/af_netlink.c:1182 [inline]
 netlink_sendmsg+0x611/0xb80 net/netlink/af_netlink.c:1898

Memory state around the buggy address:
 ffff8881124a6f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8881124a7000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8881124a7080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                     ^
 ffff8881124a7100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881124a7180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/10 07:17 android13-5.15-lts 6c35ef5f7a13 4e8b1cc6 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-5-15-perf KASAN: use-after-free Read in tipc_skb_dump
2026/09/10 06:35 android13-5.15-lts 6c35ef5f7a13 4e8b1cc6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-15-perf KASAN: use-after-free Read in tipc_skb_dump
2026/09/01 21:12 android13-5.15-lts 656ab6019045 587f6b29 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-15 KASAN: use-after-free Read in tipc_skb_dump
2026/08/31 16:06 android13-5.15-lts 54850912d011 316d9396 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-15 KASAN: use-after-free Read in tipc_skb_dump
2026/08/18 21:06 android13-5.15-lts a825653ab7af 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-15 KASAN: use-after-free Read in tipc_skb_dump
* Struck through repros no longer work on HEAD.