[PATCH 3.2 133/199] netlabel: out of bound access in cipso_v4_validate()

[Ben Hutchings]

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

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

From: Eric Dumazet <eduma...@google.com>

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 <eduma...@google.com>
Reported-by: Dmitry Vyukov  <dvyu...@google.com>
Cc: Paul Moore <p...@paul-moore.com>
Acked-by: Paul Moore <p...@paul-moore.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
 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
@@ -303,6 +303,10 @@ 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) || (opt[opt_iter + 1] > (opt_len - 
opt_iter))) {
                        err_offset = opt_iter + 1;
--- a/net/ipv4/cipso_ipv4.c
+++ b/net/ipv4/cipso_ipv4.c
@@ -1649,6 +1649,10 @@ 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;