[PATCH 6.18.y] net: mctp: ensure our nlmsg responses are initialised

[PATCH 6.18.y] net: mctp: ensure our nlmsg responses are initialised

[Li hongliang]

From: Jeremy Kerr <jk@codeconstruct.com.au>

[ Upstream commit a6a9bc544b675d8b5180f2718ec985ad267b5cbf ]

Syed Faraz Abrar (@farazsth98) from Zellic, and Pumpkin (@u1f383) from
DEVCORE Research Team working with Trend Micro Zero Day Initiative
report that a RTM_GETNEIGH will return uninitalised data in the pad
bytes of the ndmsg data.

Ensure we're initialising the netlink data to zero, in the link, addr
and neigh response messages.

Fixes: 831119f88781 ("mctp: Add neighbour netlink interface")
Fixes: 06d2f4c583a7 ("mctp: Add netlink route management")
Fixes: 583be982d934 ("mctp: Add device handling and netlink interface")
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20260209-dev-mctp-nlmsg-v1-1-f1e30c346a43@codeconstruct.com.au
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Li hongliang <1468888505@139.com>
---
 net/mctp/device.c | 1 +
 net/mctp/neigh.c  | 1 +
 net/mctp/route.c  | 1 +
 3 files changed, 3 insertions(+)

diff --git a/net/mctp/device.c b/net/mctp/device.c
index 4d404edd7446..04c5570bacff 100644
--- a/net/mctp/device.c
+++ b/net/mctp/device.c
@@ -70,6 +70,7 @@ static int mctp_fill_addrinfo(struct sk_buff *skb,
 		return -EMSGSIZE;
 
 	hdr = nlmsg_data(nlh);
+	memset(hdr, 0, sizeof(*hdr));
 	hdr->ifa_family = AF_MCTP;
 	hdr->ifa_prefixlen = 0;
 	hdr->ifa_flags = 0;
diff --git a/net/mctp/neigh.c b/net/mctp/neigh.c
index 05b899f22d90..fc85f0e69301 100644
--- a/net/mctp/neigh.c
+++ b/net/mctp/neigh.c
@@ -218,6 +218,7 @@ static int mctp_fill_neigh(struct sk_buff *skb, u32 portid, u32 seq, int event,
 		return -EMSGSIZE;
 
 	hdr = nlmsg_data(nlh);
+	memset(hdr, 0, sizeof(*hdr));
 	hdr->ndm_family = AF_MCTP;
 	hdr->ndm_ifindex = dev->ifindex;
 	hdr->ndm_state = 0; // TODO other state bits?
diff --git a/net/mctp/route.c b/net/mctp/route.c
index d4fdaac8037a..eb817f1eb5c8 100644
--- a/net/mctp/route.c
+++ b/net/mctp/route.c
@@ -1650,6 +1650,7 @@ static int mctp_fill_rtinfo(struct sk_buff *skb, struct mctp_route *rt,
 		return -EMSGSIZE;
 
 	hdr = nlmsg_data(nlh);
+	memset(hdr, 0, sizeof(*hdr));
 	hdr->rtm_family = AF_MCTP;
 
 	/* we use the _len fields as a number of EIDs, rather than
-- 
2.34.1

Re: [PATCH 6.18.y] net: mctp: ensure our nlmsg responses are initialised

[Sasha Levin]

On Tue, Jun 02, 2026 at 03:34:28PM +0800, Li hongliang wrote:
> [PATCH 6.18.y] net: mctp: ensure our nlmsg responses are initialised

Thanks. All five per-branch submissions (backports of upstream
a6a9bc544b67) are now queued.

-- 
Thanks,
Sasha