From d10119968d0e1f2b669604baf2a8b5fdb72fa6b4 Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: Mon, 6 Apr 2026 17:34:22 +0200
Subject: xfrm_user: fix info leak in build_report()

struct xfrm_user_report is a __u8 proto field followed by a struct
xfrm_selector which means there is three "empty" bytes of padding, but
the padding is never zeroed before copying to userspace.  Fix that up by
zeroing the structure before setting individual member variables.

Cc: stable <stable@kernel.org>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Simon Horman <horms@kernel.org>
Assisted-by: gregkh_clanker_t1000
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
---
 net/xfrm/xfrm_user.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index baa43c325da2..d56450f61669 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -4125,6 +4125,7 @@ static int build_report(struct sk_buff *skb, u8 proto,
 		return -EMSGSIZE;
 
 	ur = nlmsg_data(nlh);
+	memset(ur, 0, sizeof(*ur));
 	ur->proto = proto;
 	memcpy(&ur->sel, sel, sizeof(ur->sel));
 
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