FAILED: patch "[PATCH] xfrm: clear trailing padding in build_polexpire()" failed to apply to 5.15-stable tree

FAILED: patch "[PATCH] xfrm: clear trailing padding in build_polexpire()" failed to apply to 5.15-stable tree

[gregkh]

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 71a98248c63c535eaa4d4c22f099b68d902006d0
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026041331-wiring-revenge-aec2@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 71a98248c63c535eaa4d4c22f099b68d902006d0 Mon Sep 17 00:00:00 2001
From: Yasuaki Torimaru <yasuakitorimaru@gmail.com>
Date: Thu, 26 Mar 2026 14:58:00 +0900
Subject: [PATCH] xfrm: clear trailing padding in build_polexpire()

build_expire() clears the trailing padding bytes of struct
xfrm_user_expire after setting the hard field via memset_after(),
but the analogous function build_polexpire() does not do this for
struct xfrm_user_polexpire.

The padding bytes after the __u8 hard field are left
uninitialized from the heap allocation, and are then sent to
userspace via netlink multicast to XFRMNLGRP_EXPIRE listeners,
leaking kernel heap memory contents.

Add the missing memset_after() call, matching build_expire().

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Yasuaki Torimaru <yasuakitorimaru@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index 1656b487f833..5d59c11fc01e 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -3960,6 +3960,8 @@ static int build_polexpire(struct sk_buff *skb, struct xfrm_policy *xp,
 		return err;
 	}
 	upe->hard = !!hard;
+	/* clear the padding bytes */
+	memset_after(upe, 0, hard);
 
 	nlmsg_end(skb, nlh);
 	return 0;

[PATCH 5.15.y] xfrm: clear trailing padding in build_polexpire()

[Sasha Levin]

From: Yasuaki Torimaru <yasuakitorimaru@gmail.com>

[ Upstream commit 71a98248c63c535eaa4d4c22f099b68d902006d0 ]

build_expire() clears the trailing padding bytes of struct
xfrm_user_expire after setting the hard field via memset_after(),
but the analogous function build_polexpire() does not do this for
struct xfrm_user_polexpire.

The padding bytes after the __u8 hard field are left
uninitialized from the heap allocation, and are then sent to
userspace via netlink multicast to XFRMNLGRP_EXPIRE listeners,
leaking kernel heap memory contents.

Add the missing memset_after() call, matching build_expire().

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Yasuaki Torimaru <yasuakitorimaru@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
[ replaced `memset_after()` macro with equivalent manual `memset()` call ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/xfrm/xfrm_user.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index d9238e17ab427..58c61efe1d7b3 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -3389,6 +3389,8 @@ static int build_polexpire(struct sk_buff *skb, struct xfrm_policy *xp,
 		return err;
 	}
 	upe->hard = !!hard;
+	/* clear the padding bytes */
+	memset(&upe->hard + 1, 0, sizeof(*upe) - offsetofend(typeof(*upe), hard));
 
 	nlmsg_end(skb, nlh);
 	return 0;
-- 
2.53.0