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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Steffen Klassert <steffen.klassert@secunet.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 27/56] xfrm: Fix crash when the hold queue is used.
Date:   Mon,  3 Aug 2020 14:19:42 +0200
Message-Id: <20200803121851.669728405@linuxfoundation.org>
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From: Steffen Klassert <steffen.klassert@secunet.com>

[ Upstream commit 101dde4207f1daa1fda57d714814a03835dccc3f ]

The commits "xfrm: Move dst->path into struct xfrm_dst"
and "net: Create and use new helper xfrm_dst_child()."
changed xfrm bundle handling under the assumption
that xdst->path and dst->child are not a NULL pointer
only if dst->xfrm is not a NULL pointer. That is true
with one exception. If the xfrm hold queue is used
to wait until a SA is installed by the key manager,
we create a dummy bundle without a valid dst->xfrm
pointer. The current xfrm bundle handling crashes
in that case. Fix this by extending the NULL check
of dst->xfrm with a test of the DST_XFRM_QUEUE flag.

Fixes: 0f6c480f23f4 ("xfrm: Move dst->path into struct xfrm_dst")
Fixes: b92cf4aab8e6 ("net: Create and use new helper xfrm_dst_child().")
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 include/net/xfrm.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index f087c8d125b8f..3a0b5de742e9b 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -1016,7 +1016,7 @@ struct xfrm_dst {
 static inline struct dst_entry *xfrm_dst_path(const struct dst_entry *dst)
 {
 #ifdef CONFIG_XFRM
-	if (dst->xfrm) {
+	if (dst->xfrm || (dst->flags & DST_XFRM_QUEUE)) {
 		const struct xfrm_dst *xdst = (const struct xfrm_dst *) dst;
 
 		return xdst->path;
@@ -1028,7 +1028,7 @@ static inline struct dst_entry *xfrm_dst_path(const struct dst_entry *dst)
 static inline struct dst_entry *xfrm_dst_child(const struct dst_entry *dst)
 {
 #ifdef CONFIG_XFRM
-	if (dst->xfrm) {
+	if (dst->xfrm || (dst->flags & DST_XFRM_QUEUE)) {
 		struct xfrm_dst *xdst = (struct xfrm_dst *) dst;
 		return xdst->child;
 	}
-- 
2.25.1