[PATCH 3.16 275/370] netlabel: out of bound access in cipso_v4_validate()

[Ben Hutchings]

3.16.42-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Dumazet <edumazet@xxxxxxxxxx>

commit d71b7896886345c53ef1d84bda2bc758554f5d61 upstream.

syzkaller found another out of bound access in ip_options_compile(),
or more exactly in cipso_v4_validate()

Fixes: 20e2a8648596 ("cipso: handle CIPSO options correctly when NetLabel is disabled")
Fixes: 446fda4f2682 ("[NetLabel]: CIPSOv4 engine")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Reported-by: Dmitry Vyukov  <dvyukov@xxxxxxxxxx>
Cc: Paul Moore <paul@xxxxxxxxxxxxxx>
Acked-by: Paul Moore <paul@xxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 include/net/cipso_ipv4.h | 4 ++++
 net/ipv4/cipso_ipv4.c    | 4 ++++
 2 files changed, 8 insertions(+)

--- a/include/net/cipso_ipv4.h
+++ b/include/net/cipso_ipv4.h
@@ -302,6 +302,10 @@ static inline int cipso_v4_validate(cons
 	}
 
 	for (opt_iter = 6; opt_iter < opt_len;) {
+		if (opt_iter + 1 == opt_len) {
+			err_offset = opt_iter;
+			goto out;
+		}
 		tag_len = opt[opt_iter + 1];
 		if ((tag_len == 0) || (tag_len > (opt_len - opt_iter))) {
 			err_offset = opt_iter + 1;
--- a/net/ipv4/cipso_ipv4.c
+++ b/net/ipv4/cipso_ipv4.c
@@ -1645,6 +1645,10 @@ int cipso_v4_validate(const struct sk_bu
 				goto validate_return_locked;
 			}
 
+		if (opt_iter + 1 == opt_len) {
+			err_offset = opt_iter;
+			goto validate_return_locked;
+		}
 		tag_len = tag[1];
 		if (tag_len > (opt_len - opt_iter)) {
 			err_offset = opt_iter + 1;