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 <redacted>
---
 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 85cc5f31f1e7..fd368249246d 100644
--- a/net/mctp/device.c
+++ b/net/mctp/device.c

@@ -71,6 +71,7 @@ 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 590f642413e4..c0151a69d2b7 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 fdeaf80691e5..c9b0b7542243 100644
--- a/net/mctp/route.c
+++ b/net/mctp/route.c

@@ -1331,6 +1331,7 @@ 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