From: Steffen Klassert <steffen.klassert@secunet.com>
Subject: xfrm: Validate address prefix lengths in the xfrm
 selector
Patch-mainline: v4.19-rc7
Git-commit: 07bf7908950a8b14e81aa1807e3c667eab39287a
References: git-fixes


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 <icytxw@gmail.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Acked-by: Denis Kirjanov <dkirjanov@suse.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 5e8f4f3fbe6b..aff0fce28555 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -156,10 +156,16 @@ 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;
@@ -1352,10 +1358,16 @@ 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;
-- 
2.12.3