Re: [syzbot] [rdma?] KMSAN: uninit-value in ib_nl_handle_ip_res_resp
From: yanjun.zhu
Date: Thu Oct 02 2025 - 14:17:07 EST
On 9/30/25 8:02 PM, Kohei Enju wrote:
On Tue, 30 Sep 2025 13:29:32 -0700, syzbot wrote:
Hello,
syzbot found the following issue on:
HEAD commit: 1896ce8eb6c6 Merge tag 'fsverity-for-linus' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=153d0092580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6eca10e0cdef44f
dashboard link: https://syzkaller.appspot.com/bug?extid=938fcd548c303fe33c1a
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
userspace arch: i386
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d0fbab3c0b62/disk-1896ce8e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/71c7b444e106/vmlinux-1896ce8e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/96a4aa63999d/bzImage-1896ce8e.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+938fcd548c303fe33c1a@xxxxxxxxxxxxxxxxxxxxxxxxx
netlink: 8 bytes leftover after parsing attributes in process `syz.8.3246'.
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BUG: KMSAN: uninit-value in hex_byte_pack include/linux/hex.h:13 [inline]
BUG: KMSAN: uninit-value in ip6_string+0xef4/0x13a0 lib/vsprintf.c:1490
hex_byte_pack include/linux/hex.h:13 [inline]
ip6_string+0xef4/0x13a0 lib/vsprintf.c:1490
ip6_addr_string+0x18a/0x3e0 lib/vsprintf.c:1509
ip_addr_string+0x245/0xee0 lib/vsprintf.c:1633
pointer+0xc09/0x1bd0 lib/vsprintf.c:2542
vsnprintf+0xf8a/0x1bd0 lib/vsprintf.c:2930
vprintk_store+0x3ae/0x1530 kernel/printk/printk.c:2279
vprintk_emit+0x307/0xcd0 kernel/printk/printk.c:2426
vprintk_default+0x3f/0x50 kernel/printk/printk.c:2465
vprintk+0x36/0x50 kernel/printk/printk_safe.c:82
_printk+0x17e/0x1b0 kernel/printk/printk.c:2475
ib_nl_process_good_ip_rsep drivers/infiniband/core/addr.c:128 [inline]
I see when gid is not initialized in nla_for_each_attr loop, this should
return early.
GID is a globally unique 128-bit identifier for an RDMA port, used for addressing and routing in InfiniBand or RoCE networks. It’s crucial for establishing RDMA connections across subnets or Ethernet networks. IMO, we do not just return when gid is not found. We should find out why the GID does not exist if I get you correctly.
Then we can fix this problem where the GID can not be added into GID table.
It is just my 2 cent advice.
Yanjun.Zhu
I think the splat occurrs when gid is not found, so a simple fix might
be like:
diff --git a/drivers/infiniband/core/addr.c b/drivers/infiniband/core/addr.c
index be0743dac3ff..c03a308bcda5 100644
--- a/drivers/infiniband/core/addr.c
+++ b/drivers/infiniband/core/addr.c
@@ -103,15 +103,21 @@ static void ib_nl_process_good_ip_rsep(const struct nlmsghdr *nlh)
struct addr_req *req;
int len, rem;
int found = 0;
+ bool gid_found = false;
head = (const struct nlattr *)nlmsg_data(nlh);
len = nlmsg_len(nlh);
nla_for_each_attr(curr, head, len, rem) {
- if (curr->nla_type == LS_NLA_TYPE_DGID)
+ if (curr->nla_type == LS_NLA_TYPE_DGID) {
memcpy(&gid, nla_data(curr), nla_len(curr));
+ gid_found = true;
+ }
}
+ if (!gid_found)
+ return;
+
spin_lock_bh(&lock);
list_for_each_entry(req, &req_list, list) {
if (nlh->nlmsg_seq != req->seq)
ib_nl_handle_ip_res_resp+0x963/0x9d0 drivers/infiniband/core/addr.c:141
rdma_nl_rcv_msg drivers/infiniband/core/netlink.c:-1 [inline]
rdma_nl_rcv_skb drivers/infiniband/core/netlink.c:239 [inline]
rdma_nl_rcv+0xefa/0x11c0 drivers/infiniband/core/netlink.c:259
netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
netlink_unicast+0xf04/0x12b0 net/netlink/af_netlink.c:1346
netlink_sendmsg+0x10b3/0x1250 net/netlink/af_netlink.c:1896
sock_sendmsg_nosec net/socket.c:714 [inline]
__sock_sendmsg+0x333/0x3d0 net/socket.c:729
____sys_sendmsg+0x7e0/0xd80 net/socket.c:2617
___sys_sendmsg+0x271/0x3b0 net/socket.c:2671
__sys_sendmsg+0x1aa/0x300 net/socket.c:2703
__compat_sys_sendmsg net/compat.c:346 [inline]
__do_compat_sys_sendmsg net/compat.c:353 [inline]
__se_compat_sys_sendmsg net/compat.c:350 [inline]
__ia32_compat_sys_sendmsg+0xa4/0x100 net/compat.c:350
ia32_sys_call+0x3f6c/0x4310 arch/x86/include/generated/asm/syscalls_32.h:371
do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
__do_fast_syscall_32+0xb0/0x150 arch/x86/entry/syscall_32.c:306
do_fast_syscall_32+0x38/0x80 arch/x86/entry/syscall_32.c:331
do_SYSENTER_32+0x1f/0x30 arch/x86/entry/syscall_32.c:369
entry_SYSENTER_compat_after_hwframe+0x84/0x8e
Local variable gid.i created at:
ib_nl_process_good_ip_rsep drivers/infiniband/core/addr.c:102 [inline]
ib_nl_handle_ip_res_resp+0x254/0x9d0 drivers/infiniband/core/addr.c:141
rdma_nl_rcv_msg drivers/infiniband/core/netlink.c:-1 [inline]
rdma_nl_rcv_skb drivers/infiniband/core/netlink.c:239 [inline]
rdma_nl_rcv+0xefa/0x11c0 drivers/infiniband/core/netlink.c:259
CPU: 0 UID: 0 PID: 17455 Comm: syz.8.3246 Not tainted syzkaller #0 PREEMPT(none)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
=====================================================
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