[PATCH 1/6] xfrm: Validate address prefix lengths in the xfrm selector.

[Steffen Klassert]

We don't validate the address prefix lengths in the xfrm
selector we got from userspace. This can lead to undefined
behaviour in the address matching functions if the prefix
is too big for the given address family. Fix this by checking
the prefixes and refuse SA/policy insertation when a prefix
is invalid.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-by: Air Icy <icy...@gmail.com>
Signed-off-by: Steffen Klassert <steffen.klass...@secunet.com>
---
 net/xfrm/xfrm_user.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index 33878e6e0d0a..5151b3ebf068 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -151,10 +151,16 @@ static int verify_newsa_info(struct xfrm_usersa_info *p,
        err = -EINVAL;
        switch (p->family) {
        case AF_INET:
+               if (p->sel.prefixlen_d > 32 || p->sel.prefixlen_s > 32)
+                       goto out;
+
                break;
 
        case AF_INET6:
 #if IS_ENABLED(CONFIG_IPV6)
+               if (p->sel.prefixlen_d > 128 || p->sel.prefixlen_s > 128)
+                       goto out;
+
                break;
 #else
                err = -EAFNOSUPPORT;
@@ -1359,10 +1365,16 @@ static int verify_newpolicy_info(struct 
xfrm_userpolicy_info *p)
 
        switch (p->sel.family) {
        case AF_INET:
+               if (p->sel.prefixlen_d > 32 || p->sel.prefixlen_s > 32)
+                       return -EINVAL;
+
                break;
 
        case AF_INET6:
 #if IS_ENABLED(CONFIG_IPV6)
+               if (p->sel.prefixlen_d > 128 || p->sel.prefixlen_s > 128)
+                       return -EINVAL;
+
                break;
 #else
                return  -EAFNOSUPPORT;
-- 
2.17.1