4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Herbert Xu herbert@gondor.apana.org.au
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 herbert@gondor.apana.org.au Signed-off-by: Steffen Klassert steffen.klassert@secunet.com Cc: Guenter Roeck linux@roeck-us.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/xfrm/xfrm_user.c | 25 +++++++++++++++---------- 1 file changed, 15 insertions(+), 10 deletions(-)
--- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -1652,32 +1652,34 @@ 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, };