[moderation] [net?] KASAN: slab-use-after-free Write in arp_create
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syzbot
Jan 7, 2026, 12:04:22 PM (yesterday) Jan 7
to syzkaller-upst...@googlegroups.com
Hello,
syzbot found the following issue on:
HEAD commit: 8e7148b56023 atm: idt77252: Use sb_pool_remove()
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1253c1fc580000
kernel config: https://syzkaller.appspot.com/x/.config?x=a94030c847137a18
dashboard link: https://syzkaller.appspot.com/bug?extid=0a9216b3bdba3f925ba1
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
CC: [da...@davemloft.net dsa...@kernel.org edum...@google.com ho...@kernel.org ku...@kernel.org linux-...@vger.kernel.org net...@vger.kernel.org pab...@redhat.com]
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/2913fe5e8157/disk-8e7148b5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f91ee7db4b2e/vmlinux-8e7148b5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e5ce7b3f1144/bzImage-8e7148b5.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0a9216...@syzkaller.appspotmail.com
sit0: left promiscuous mode
ip6gre0: left promiscuous mode
==================================================================
BUG: KASAN: slab-use-after-free in arp_create+0x859/0x990 net/ipv4/arp.c:-1
Write of size 2 at addr ffff888031c51d50 by task syz.3.2633/16059
CPU: 0 UID: 0 PID: 16059 Comm: syz.3.2633 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 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
arp_create+0x859/0x990 net/ipv4/arp.c:-1
arp_send_dst net/ipv4/arp.c:314 [inline]
arp_send+0xa5/0x190 net/ipv4/arp.c:328
inetdev_send_gratuitous_arp net/ipv4/devinet.c:1571 [inline]
inetdev_event+0x1156/0x15b0 net/ipv4/devinet.c:1638
notifier_call_chain+0x19d/0x3a0 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:9803
do_setlink+0xc55/0x41c0 net/core/rtnetlink.c:3158
rtnl_group_changelink net/core/rtnetlink.c:3790 [inline]
__rtnl_newlink net/core/rtnetlink.c:3944 [inline]
rtnl_newlink+0x14b0/0x1c90 net/core/rtnetlink.c:4072
rtnetlink_rcv_msg+0x7cf/0xb70 net/core/rtnetlink.c:6958
netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2550
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x82f/0x9e0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg+0x21c/0x270 net/socket.c:742
____sys_sendmsg+0x505/0x820 net/socket.c:2592
___sys_sendmsg+0x21f/0x2a0 net/socket.c:2646
__sys_sendmsg net/socket.c:2678 [inline]
__do_sys_sendmsg net/socket.c:2683 [inline]
__se_sys_sendmsg net/socket.c:2681 [inline]
__x64_sys_sendmsg+0x19b/0x260 net/socket.c:2681
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f50a2d8f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f50a3c64038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f50a2fe6180 RCX: 00007f50a2d8f749
RDX: 0000000000000000 RSI: 0000200000000140 RDI: 000000000000000d
RBP: 00007f50a2e13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f50a2fe6218 R14: 00007f50a2fe6180 R15: 00007ffe4aa758d8
</TASK>
Allocated by task 16059:
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
unpoison_slab_object mm/kasan/common.c:340 [inline]
__kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
kasan_slab_alloc include/linux/kasan.h:253 [inline]
slab_post_alloc_hook mm/slub.c:4953 [inline]
slab_alloc_node mm/slub.c:5263 [inline]
kmem_cache_alloc_node_noprof+0x43c/0x720 mm/slub.c:5315
kmalloc_reserve+0xbd/0x290 net/core/skbuff.c:586
__alloc_skb+0x204/0x3a0 net/core/skbuff.c:690
alloc_skb include/linux/skbuff.h:1383 [inline]
arp_create+0x189/0x990 net/ipv4/arp.c:561
arp_send_dst net/ipv4/arp.c:314 [inline]
arp_send+0xa5/0x190 net/ipv4/arp.c:328
inetdev_send_gratuitous_arp net/ipv4/devinet.c:1571 [inline]
inetdev_event+0x1156/0x15b0 net/ipv4/devinet.c:1638
notifier_call_chain+0x19d/0x3a0 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:9803
do_setlink+0xc55/0x41c0 net/core/rtnetlink.c:3158
rtnl_group_changelink net/core/rtnetlink.c:3790 [inline]
__rtnl_newlink net/core/rtnetlink.c:3944 [inline]
rtnl_newlink+0x14b0/0x1c90 net/core/rtnetlink.c:4072
rtnetlink_rcv_msg+0x7cf/0xb70 net/core/rtnetlink.c:6958
netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2550
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x82f/0x9e0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg+0x21c/0x270 net/socket.c:742
____sys_sendmsg+0x505/0x820 net/socket.c:2592
___sys_sendmsg+0x21f/0x2a0 net/socket.c:2646
__sys_sendmsg net/socket.c:2678 [inline]
__do_sys_sendmsg net/socket.c:2683 [inline]
__se_sys_sendmsg net/socket.c:2681 [inline]
__x64_sys_sendmsg+0x19b/0x260 net/socket.c:2681
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 16059:
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:2540 [inline]
slab_free mm/slub.c:6670 [inline]
kmem_cache_free+0x197/0x620 mm/slub.c:6781
pskb_expand_head+0x39e/0x1160 net/core/skbuff.c:2314
ip6gre_header+0x13c/0x820 net/ipv6/ip6_gre.c:1376
dev_hard_header include/linux/netdevice.h:3436 [inline]
arp_create+0x3fd/0x990 net/ipv4/arp.c:578
arp_send_dst net/ipv4/arp.c:314 [inline]
arp_send+0xa5/0x190 net/ipv4/arp.c:328
inetdev_send_gratuitous_arp net/ipv4/devinet.c:1571 [inline]
inetdev_event+0x1156/0x15b0 net/ipv4/devinet.c:1638
notifier_call_chain+0x19d/0x3a0 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:9803
do_setlink+0xc55/0x41c0 net/core/rtnetlink.c:3158
rtnl_group_changelink net/core/rtnetlink.c:3790 [inline]
__rtnl_newlink net/core/rtnetlink.c:3944 [inline]
rtnl_newlink+0x14b0/0x1c90 net/core/rtnetlink.c:4072
rtnetlink_rcv_msg+0x7cf/0xb70 net/core/rtnetlink.c:6958
netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2550
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x82f/0x9e0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg+0x21c/0x270 net/socket.c:742
____sys_sendmsg+0x505/0x820 net/socket.c:2592
___sys_sendmsg+0x21f/0x2a0 net/socket.c:2646
__sys_sendmsg net/socket.c:2678 [inline]
__do_sys_sendmsg net/socket.c:2683 [inline]
__se_sys_sendmsg net/socket.c:2681 [inline]
__x64_sys_sendmsg+0x19b/0x260 net/socket.c:2681
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
The buggy address belongs to the object at ffff888031c51d40
which belongs to the cache skbuff_small_head of size 704
The buggy address is located 16 bytes inside of
freed 704-byte region [ffff888031c51d40, ffff888031c52000)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x31c50
head: order:2 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 ffff88801d6e1c80 dead000000000122 0000000000000000
raw: 0000000000000000 0000000080130013 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801d6e1c80 dead000000000122 0000000000000000
head: 0000000000000000 0000000080130013 00000000f5000000 0000000000000000
head: 00fff00000000002 ffffea0000c71401 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 16059, tgid 16050 (syz.3.2633), ts 579733121729, free_ts 429869578042
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x234/0x290 mm/page_alloc.c:1857
prep_new_page mm/page_alloc.c:1865 [inline]
get_page_from_freelist+0x24e0/0x2580 mm/page_alloc.c:3915
__alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5210
alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2486
alloc_slab_page mm/slub.c:3075 [inline]
allocate_slab+0x86/0x3b0 mm/slub.c:3248
new_slab mm/slub.c:3302 [inline]
___slab_alloc+0xe53/0x1820 mm/slub.c:4656
__slab_alloc+0x65/0x100 mm/slub.c:4779
__slab_alloc_node mm/slub.c:4855 [inline]
slab_alloc_node mm/slub.c:5251 [inline]
kmem_cache_alloc_node_noprof+0x4ce/0x720 mm/slub.c:5315
kmalloc_reserve+0xbd/0x290 net/core/skbuff.c:586
__alloc_skb+0x204/0x3a0 net/core/skbuff.c:690
alloc_skb include/linux/skbuff.h:1383 [inline]
nlmsg_new include/net/netlink.h:1055 [inline]
inet_ifmcaddr_notify+0x7e/0x150 net/ipv4/igmp.c:1481
____ip_mc_inc_group+0x9a8/0xdd0 net/ipv4/igmp.c:1564
__ip_mc_inc_group net/ipv4/igmp.c:1573 [inline]
ip_mc_inc_group net/ipv4/igmp.c:1579 [inline]
ip_mc_up+0x115/0x2e0 net/ipv4/igmp.c:1880
inetdev_event+0xf93/0x15b0 net/ipv4/devinet.c:1630
notifier_call_chain+0x19d/0x3a0 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
page last free pid 5186 tgid 5186 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1406 [inline]
__free_frozen_pages+0xbc8/0xd30 mm/page_alloc.c:2943
__slab_free+0x2ce/0x320 mm/slub.c:6004
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x97/0x100 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:4953 [inline]
slab_alloc_node mm/slub.c:5263 [inline]
__do_kmalloc_node mm/slub.c:5656 [inline]
__kmalloc_node_track_caller_noprof+0x526/0x820 mm/slub.c:5764
kmalloc_reserve+0x136/0x290 net/core/skbuff.c:608
__alloc_skb+0x204/0x3a0 net/core/skbuff.c:690
alloc_skb include/linux/skbuff.h:1383 [inline]
alloc_skb_with_frags+0xca/0x890 net/core/skbuff.c:6712
sock_alloc_send_pskb+0x84d/0x980 net/core/sock.c:2995
unix_dgram_sendmsg+0x454/0x1840 net/unix/af_unix.c:2130
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg+0x21c/0x270 net/socket.c:742
__sys_sendto+0x3bd/0x520 net/socket.c:2206
__do_sys_sendto net/socket.c:2213 [inline]
__se_sys_sendto net/socket.c:2209 [inline]
__x64_sys_sendto+0xde/0x100 net/socket.c:2209
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Memory state around the buggy address:
ffff888031c51c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888031c51c80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff888031c51d00: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
^
ffff888031c51d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888031c51e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
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(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
syzbot found the following issue on:
HEAD commit: 8e7148b56023 atm: idt77252: Use sb_pool_remove()
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1253c1fc580000
kernel config: https://syzkaller.appspot.com/x/.config?x=a94030c847137a18
dashboard link: https://syzkaller.appspot.com/bug?extid=0a9216b3bdba3f925ba1
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
CC: [da...@davemloft.net dsa...@kernel.org edum...@google.com ho...@kernel.org ku...@kernel.org linux-...@vger.kernel.org net...@vger.kernel.org pab...@redhat.com]
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/2913fe5e8157/disk-8e7148b5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f91ee7db4b2e/vmlinux-8e7148b5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e5ce7b3f1144/bzImage-8e7148b5.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0a9216...@syzkaller.appspotmail.com
sit0: left promiscuous mode
ip6gre0: left promiscuous mode
==================================================================
BUG: KASAN: slab-use-after-free in arp_create+0x859/0x990 net/ipv4/arp.c:-1
Write of size 2 at addr ffff888031c51d50 by task syz.3.2633/16059
CPU: 0 UID: 0 PID: 16059 Comm: syz.3.2633 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 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
arp_create+0x859/0x990 net/ipv4/arp.c:-1
arp_send_dst net/ipv4/arp.c:314 [inline]
arp_send+0xa5/0x190 net/ipv4/arp.c:328
inetdev_send_gratuitous_arp net/ipv4/devinet.c:1571 [inline]
inetdev_event+0x1156/0x15b0 net/ipv4/devinet.c:1638
notifier_call_chain+0x19d/0x3a0 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:9803
do_setlink+0xc55/0x41c0 net/core/rtnetlink.c:3158
rtnl_group_changelink net/core/rtnetlink.c:3790 [inline]
__rtnl_newlink net/core/rtnetlink.c:3944 [inline]
rtnl_newlink+0x14b0/0x1c90 net/core/rtnetlink.c:4072
rtnetlink_rcv_msg+0x7cf/0xb70 net/core/rtnetlink.c:6958
netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2550
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x82f/0x9e0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg+0x21c/0x270 net/socket.c:742
____sys_sendmsg+0x505/0x820 net/socket.c:2592
___sys_sendmsg+0x21f/0x2a0 net/socket.c:2646
__sys_sendmsg net/socket.c:2678 [inline]
__do_sys_sendmsg net/socket.c:2683 [inline]
__se_sys_sendmsg net/socket.c:2681 [inline]
__x64_sys_sendmsg+0x19b/0x260 net/socket.c:2681
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f50a2d8f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f50a3c64038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f50a2fe6180 RCX: 00007f50a2d8f749
RDX: 0000000000000000 RSI: 0000200000000140 RDI: 000000000000000d
RBP: 00007f50a2e13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f50a2fe6218 R14: 00007f50a2fe6180 R15: 00007ffe4aa758d8
</TASK>
Allocated by task 16059:
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
unpoison_slab_object mm/kasan/common.c:340 [inline]
__kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
kasan_slab_alloc include/linux/kasan.h:253 [inline]
slab_post_alloc_hook mm/slub.c:4953 [inline]
slab_alloc_node mm/slub.c:5263 [inline]
kmem_cache_alloc_node_noprof+0x43c/0x720 mm/slub.c:5315
kmalloc_reserve+0xbd/0x290 net/core/skbuff.c:586
__alloc_skb+0x204/0x3a0 net/core/skbuff.c:690
alloc_skb include/linux/skbuff.h:1383 [inline]
arp_create+0x189/0x990 net/ipv4/arp.c:561
arp_send_dst net/ipv4/arp.c:314 [inline]
arp_send+0xa5/0x190 net/ipv4/arp.c:328
inetdev_send_gratuitous_arp net/ipv4/devinet.c:1571 [inline]
inetdev_event+0x1156/0x15b0 net/ipv4/devinet.c:1638
notifier_call_chain+0x19d/0x3a0 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:9803
do_setlink+0xc55/0x41c0 net/core/rtnetlink.c:3158
rtnl_group_changelink net/core/rtnetlink.c:3790 [inline]
__rtnl_newlink net/core/rtnetlink.c:3944 [inline]
rtnl_newlink+0x14b0/0x1c90 net/core/rtnetlink.c:4072
rtnetlink_rcv_msg+0x7cf/0xb70 net/core/rtnetlink.c:6958
netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2550
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x82f/0x9e0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg+0x21c/0x270 net/socket.c:742
____sys_sendmsg+0x505/0x820 net/socket.c:2592
___sys_sendmsg+0x21f/0x2a0 net/socket.c:2646
__sys_sendmsg net/socket.c:2678 [inline]
__do_sys_sendmsg net/socket.c:2683 [inline]
__se_sys_sendmsg net/socket.c:2681 [inline]
__x64_sys_sendmsg+0x19b/0x260 net/socket.c:2681
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 16059:
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:2540 [inline]
slab_free mm/slub.c:6670 [inline]
kmem_cache_free+0x197/0x620 mm/slub.c:6781
pskb_expand_head+0x39e/0x1160 net/core/skbuff.c:2314
ip6gre_header+0x13c/0x820 net/ipv6/ip6_gre.c:1376
dev_hard_header include/linux/netdevice.h:3436 [inline]
arp_create+0x3fd/0x990 net/ipv4/arp.c:578
arp_send_dst net/ipv4/arp.c:314 [inline]
arp_send+0xa5/0x190 net/ipv4/arp.c:328
inetdev_send_gratuitous_arp net/ipv4/devinet.c:1571 [inline]
inetdev_event+0x1156/0x15b0 net/ipv4/devinet.c:1638
notifier_call_chain+0x19d/0x3a0 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:9803
do_setlink+0xc55/0x41c0 net/core/rtnetlink.c:3158
rtnl_group_changelink net/core/rtnetlink.c:3790 [inline]
__rtnl_newlink net/core/rtnetlink.c:3944 [inline]
rtnl_newlink+0x14b0/0x1c90 net/core/rtnetlink.c:4072
rtnetlink_rcv_msg+0x7cf/0xb70 net/core/rtnetlink.c:6958
netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2550
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x82f/0x9e0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg+0x21c/0x270 net/socket.c:742
____sys_sendmsg+0x505/0x820 net/socket.c:2592
___sys_sendmsg+0x21f/0x2a0 net/socket.c:2646
__sys_sendmsg net/socket.c:2678 [inline]
__do_sys_sendmsg net/socket.c:2683 [inline]
__se_sys_sendmsg net/socket.c:2681 [inline]
__x64_sys_sendmsg+0x19b/0x260 net/socket.c:2681
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
The buggy address belongs to the object at ffff888031c51d40
which belongs to the cache skbuff_small_head of size 704
The buggy address is located 16 bytes inside of
freed 704-byte region [ffff888031c51d40, ffff888031c52000)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x31c50
head: order:2 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 ffff88801d6e1c80 dead000000000122 0000000000000000
raw: 0000000000000000 0000000080130013 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801d6e1c80 dead000000000122 0000000000000000
head: 0000000000000000 0000000080130013 00000000f5000000 0000000000000000
head: 00fff00000000002 ffffea0000c71401 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 16059, tgid 16050 (syz.3.2633), ts 579733121729, free_ts 429869578042
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x234/0x290 mm/page_alloc.c:1857
prep_new_page mm/page_alloc.c:1865 [inline]
get_page_from_freelist+0x24e0/0x2580 mm/page_alloc.c:3915
__alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5210
alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2486
alloc_slab_page mm/slub.c:3075 [inline]
allocate_slab+0x86/0x3b0 mm/slub.c:3248
new_slab mm/slub.c:3302 [inline]
___slab_alloc+0xe53/0x1820 mm/slub.c:4656
__slab_alloc+0x65/0x100 mm/slub.c:4779
__slab_alloc_node mm/slub.c:4855 [inline]
slab_alloc_node mm/slub.c:5251 [inline]
kmem_cache_alloc_node_noprof+0x4ce/0x720 mm/slub.c:5315
kmalloc_reserve+0xbd/0x290 net/core/skbuff.c:586
__alloc_skb+0x204/0x3a0 net/core/skbuff.c:690
alloc_skb include/linux/skbuff.h:1383 [inline]
nlmsg_new include/net/netlink.h:1055 [inline]
inet_ifmcaddr_notify+0x7e/0x150 net/ipv4/igmp.c:1481
____ip_mc_inc_group+0x9a8/0xdd0 net/ipv4/igmp.c:1564
__ip_mc_inc_group net/ipv4/igmp.c:1573 [inline]
ip_mc_inc_group net/ipv4/igmp.c:1579 [inline]
ip_mc_up+0x115/0x2e0 net/ipv4/igmp.c:1880
inetdev_event+0xf93/0x15b0 net/ipv4/devinet.c:1630
notifier_call_chain+0x19d/0x3a0 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
page last free pid 5186 tgid 5186 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1406 [inline]
__free_frozen_pages+0xbc8/0xd30 mm/page_alloc.c:2943
__slab_free+0x2ce/0x320 mm/slub.c:6004
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x97/0x100 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:4953 [inline]
slab_alloc_node mm/slub.c:5263 [inline]
__do_kmalloc_node mm/slub.c:5656 [inline]
__kmalloc_node_track_caller_noprof+0x526/0x820 mm/slub.c:5764
kmalloc_reserve+0x136/0x290 net/core/skbuff.c:608
__alloc_skb+0x204/0x3a0 net/core/skbuff.c:690
alloc_skb include/linux/skbuff.h:1383 [inline]
alloc_skb_with_frags+0xca/0x890 net/core/skbuff.c:6712
sock_alloc_send_pskb+0x84d/0x980 net/core/sock.c:2995
unix_dgram_sendmsg+0x454/0x1840 net/unix/af_unix.c:2130
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg+0x21c/0x270 net/socket.c:742
__sys_sendto+0x3bd/0x520 net/socket.c:2206
__do_sys_sendto net/socket.c:2213 [inline]
__se_sys_sendto net/socket.c:2209 [inline]
__x64_sys_sendto+0xde/0x100 net/socket.c:2209
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Memory state around the buggy address:
ffff888031c51c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888031c51c80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff888031c51d00: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
^
ffff888031c51d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888031c51e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.
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Aleksandr Nogikh
Jan 7, 2026, 4:00:10 PM (23 hours ago) Jan 7
to syzbot, syzkaller-upst...@googlegroups.com
#syz upstream
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