[syzbot ci] Re: netfilter: nft_set_rbtree: allocate same array size on updates

[syzbot ci]

syzbot ci has tested the following series

[v1] netfilter: nft_set_rbtree: allocate same array size on updates
https://lore.kernel.org/all/20260306123649....@netfilter.org
* [PATCH nf] netfilter: nft_set_rbtree: allocate same array size on updates

and found the following issue:
general protection fault in nft_array_may_resize

Full report is available here:
https://ci.syzbot.org/series/63a7af7e-7e81-40b3-ac44-4a537af34cdf

***

general protection fault in nft_array_may_resize

tree: nf
URL: https://kernel.googlesource.com/pub/scm/linux/kernel/git/netfilter/nf.git
base: 488f6400e447d446ff4d5daef6988f3403dd948d
arch: amd64
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config: https://ci.syzbot.org/builds/7f67fa0a-1740-40ec-b191-899f77dd02ce/config
C repro: https://ci.syzbot.org/findings/c4666971-4767-49ca-b29d-854930c3aace/c_repro
syz repro: https://ci.syzbot.org/findings/c4666971-4767-49ca-b29d-854930c3aace/syz_repro

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 UID: 0 PID: 5957 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:nft_array_may_resize+0x17f/0x3d0 net/netfilter/nft_set_rbtree.c:649
Code: 00 00 00 49 81 c7 38 01 00 00 4c 89 f8 48 c1 e8 03 42 80 3c 28 00 74 08 4c 89 ff e8 1b de 4f f8 4d 8b 3f 4c 89 f8 48 c1 e8 03 <42> 0f b6 04 28 84 c0 0f 85 e3 01 00 00 41 8b 2f 48 c7 c0 a8 c2 1a
RSP: 0018:ffffc9000591ecc8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000002 RCX: 0000000000000000
RDX: ffff88816dced700 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000001 R08: ffff8881012f8473 R09: 1ffff1102025f08e
R10: dffffc0000000000 R11: ffffed102025f08f R12: ffff8881012f8540
R13: dffffc0000000000 R14: 1ffff1102025f0a8 R15: 0000000000000000
FS: 000055557f50a500(0000) GS:ffff88818de64000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000009b40 CR3: 000000016f370000 CR4: 00000000000006f0
Call Trace:
<TASK>
nft_rbtree_insert+0x161/0x2c00 net/netfilter/nft_set_rbtree.c:678
nft_add_set_elem net/netfilter/nf_tables_api.c:7486 [inline]
nf_tables_newsetelem+0x2a17/0x4450 net/netfilter/nf_tables_api.c:7618
nfnetlink_rcv_batch net/netfilter/nfnetlink.c:526 [inline]
nfnetlink_rcv_skb_batch net/netfilter/nfnetlink.c:649 [inline]
nfnetlink_rcv+0x1240/0x27b0 net/netfilter/nfnetlink.c:667
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x80f/0x9b0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg net/socket.c:742 [inline]
____sys_sendmsg+0x972/0x9f0 net/socket.c:2592
___sys_sendmsg+0x2a5/0x360 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+0x1bd/0x2a0 net/socket.c:2681
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fdff099c799
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:00007fff596fb518 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fdff0c15fa0 RCX: 00007fdff099c799
RDX: 0000000000000040 RSI: 0000200000009b40 RDI: 0000000000000003
RBP: 00007fdff0a32bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fdff0c15fac R14: 00007fdff0c15fa0 R15: 00007fdff0c15fa0
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:nft_array_may_resize+0x17f/0x3d0 net/netfilter/nft_set_rbtree.c:649
Code: 00 00 00 49 81 c7 38 01 00 00 4c 89 f8 48 c1 e8 03 42 80 3c 28 00 74 08 4c 89 ff e8 1b de 4f f8 4d 8b 3f 4c 89 f8 48 c1 e8 03 <42> 0f b6 04 28 84 c0 0f 85 e3 01 00 00 41 8b 2f 48 c7 c0 a8 c2 1a
RSP: 0018:ffffc9000591ecc8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000002 RCX: 0000000000000000
RDX: ffff88816dced700 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000001 R08: ffff8881012f8473 R09: 1ffff1102025f08e
R10: dffffc0000000000 R11: ffffed102025f08f R12: ffff8881012f8540
R13: dffffc0000000000 R14: 1ffff1102025f0a8 R15: 0000000000000000
FS: 000055557f50a500(0000) GS:ffff88818de64000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000009b40 CR3: 000000016f370000 CR4: 00000000000006f0
----------------
Code disassembly (best guess), 1 bytes skipped:
0: 00 00 add %al,(%rax)
2: 49 81 c7 38 01 00 00 add $0x138,%r15
9: 4c 89 f8 mov %r15,%rax
c: 48 c1 e8 03 shr $0x3,%rax
10: 42 80 3c 28 00 cmpb $0x0,(%rax,%r13,1)
15: 74 08 je 0x1f
17: 4c 89 ff mov %r15,%rdi
1a: e8 1b de 4f f8 call 0xf84fde3a
1f: 4d 8b 3f mov (%r15),%r15
22: 4c 89 f8 mov %r15,%rax
25: 48 c1 e8 03 shr $0x3,%rax
* 29: 42 0f b6 04 28 movzbl (%rax,%r13,1),%eax <-- trapping instruction
2e: 84 c0 test %al,%al
30: 0f 85 e3 01 00 00 jne 0x219
36: 41 8b 2f mov (%r15),%ebp
39: 48 rex.W
3a: c7 .byte 0xc7
3b: c0 .byte 0xc0
3c: a8 c2 test $0xc2,%al
3e: 1a .byte 0x1a


***

If these findings have caused you to resend the series or submit a
separate fix, please add the following tag to your commit message:
Tested-by: syz...@syzkaller.appspotmail.com

---
This report is generated by a bot. It may contain errors.
syzbot ci engineers can be reached at syzk...@googlegroups.com.

[Pablo Neira Ayuso]

On Sat, Mar 07, 2026 at 10:58:42AM -0800, syzbot ci wrote:
> syzbot ci has tested the following series
>
> [v1] netfilter: nft_set_rbtree: allocate same array size on updates
> https://lore.kernel.org/all/20260306123649....@netfilter.org
> * [PATCH nf] netfilter: nft_set_rbtree: allocate same array size on updates
>
> and found the following issue:
> general protection fault in nft_array_may_resize
>
> Full report is available here:

> https://ci.syzbot.org/series/63a7af7e-7e81-40b3-ac44-4a537af34cdfi

For the record, this is fixed in v2:

https://patchwork.ozlabs.org/project/netfilter-devel/patch/20260307001124....@netfilter.org/