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Patch "ipsec: Fix aborted xfrm policy dump crash" has been added to the 4.9-stable tree

PATCH [email protected] 1 participant 1 message Oct 30, 2017

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This is a note to let you know that I've just added the patch titled

ipsec: Fix aborted xfrm policy dump crash

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
ipsec-fix-aborted-xfrm-policy-dump-crash.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From 1137b5e2529a8f5ca8ee709288ecba3e68044df2 Mon Sep 17 00:00:00 2001

From: Herbert Xu <[email protected]>
Date: Thu, 19 Oct 2017 20:51:10 +0800
Subject: ipsec: Fix aborted xfrm policy dump crash

From: Herbert Xu <[email protected]>

commit 1137b5e2529a8f5ca8ee709288ecba3e68044df2 upstream.

An independent security researcher, Mohamed Ghannam, has reported this vulnerability to Beyond Security's SecuriTeam Secure Disclosure program.

The xfrm_dump_policy_done function expects xfrm_dump_policy to have been called at least once or it will crash. This can be triggered if a dump fails because the target socket's receive buffer is full.

This patch fixes it by using the cb->start mechanism to ensure that the initialisation is always done regardless of the buffer situation.

Fixes 12a169e7d8f4 ("ipsec: Put dumpers on the dump list")
Signed-off-by Herbert Xu <[email protected]>
Signed-off-by Steffen Klassert <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 net/xfrm/xfrm_user.c |   25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)
net/xfrm/xfrm_user.c +15 -10
@@ -1656,32 +1656,34 @@ static int dump_one_policy(struct xfrm_p
 
 static int xfrm_dump_policy_done(struct netlink_callback *cb)
 {
-	struct xfrm_policy_walk *walk = (struct xfrm_policy_walk *) &cb->args[1];
+	struct xfrm_policy_walk *walk = (struct xfrm_policy_walk *)cb->args;
 	struct net *net = sock_net(cb->skb->sk);
 
 	xfrm_policy_walk_done(walk, net);
 	return 0;
 }
 
+static int xfrm_dump_policy_start(struct netlink_callback *cb)
+{
+	struct xfrm_policy_walk *walk = (struct xfrm_policy_walk *)cb->args;
+
+	BUILD_BUG_ON(sizeof(*walk) > sizeof(cb->args));
+
+	xfrm_policy_walk_init(walk, XFRM_POLICY_TYPE_ANY);
+	return 0;
+}
+
 static int xfrm_dump_policy(struct sk_buff *skb, struct netlink_callback *cb)
 {
 	struct net *net = sock_net(skb->sk);
-	struct xfrm_policy_walk *walk = (struct xfrm_policy_walk *) &cb->args[1];
+	struct xfrm_policy_walk *walk = (struct xfrm_policy_walk *)cb->args;
 	struct xfrm_dump_info info;
 
-	BUILD_BUG_ON(sizeof(struct xfrm_policy_walk) >
-		     sizeof(cb->args) - sizeof(cb->args[0]));
-
 	info.in_skb = cb->skb;
 	info.out_skb = skb;
 	info.nlmsg_seq = cb->nlh->nlmsg_seq;
 	info.nlmsg_flags = NLM_F_MULTI;
 
-	if (!cb->args[0]) {
-		cb->args[0] = 1;
-		xfrm_policy_walk_init(walk, XFRM_POLICY_TYPE_ANY);
-	}
-
 	(void) xfrm_policy_walk(net, walk, dump_one_policy, &info);
 
 	return skb->len;

@@ -2415,6 +2417,7 @@ static const struct nla_policy xfrma_spd
 
 static const struct xfrm_link {
 	int (*doit)(struct sk_buff *, struct nlmsghdr *, struct nlattr **);
+	int (*start)(struct netlink_callback *);
 	int (*dump)(struct sk_buff *, struct netlink_callback *);
 	int (*done)(struct netlink_callback *);
 	const struct nla_policy *nla_pol;

@@ -2428,6 +2431,7 @@ static const struct xfrm_link {
 	[XFRM_MSG_NEWPOLICY   - XFRM_MSG_BASE] = { .doit = xfrm_add_policy    },
 	[XFRM_MSG_DELPOLICY   - XFRM_MSG_BASE] = { .doit = xfrm_get_policy    },
 	[XFRM_MSG_GETPOLICY   - XFRM_MSG_BASE] = { .doit = xfrm_get_policy,
+						   .start = xfrm_dump_policy_start,
 						   .dump = xfrm_dump_policy,
 						   .done = xfrm_dump_policy_done },
 	[XFRM_MSG_ALLOCSPI    - XFRM_MSG_BASE] = { .doit = xfrm_alloc_userspi },

@@ -2479,6 +2483,7 @@ static int xfrm_user_rcv_msg(struct sk_b
 
 		{
 			struct netlink_dump_control c = {
+				.start = link->start,
 				.dump = link->dump,
 				.done = link->done,
 			};

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/ipsec-fix-aborted-xfrm-policy-dump-crash.patch