MFC, fix by moritz:OPENBSD_4_1

The SSL_get_shared_ciphers() function contains an off-by-one overflow.

1 files changed, 12 insertions, 15 deletions

diff --git a/src/lib/libssl/src/ssl/ssl_lib.c b/src/lib/libssl/src/ssl/ssl_lib.c
index 4e8f302a5e..0f4b7a475b 100644
--- a/src/lib/libssl/src/ssl/ssl_lib.c
+++ b/src/lib/libssl/src/ssl/ssl_lib.c
@@ -1168,36 +1168,33 @@ int SSL_set_cipher_list(SSL *s,const char *str)
 /* works well for SSLv2, not so good for SSLv3 */
 char *SSL_get_shared_ciphers(const SSL *s,char *buf,int len)
         {
-        char *p;
-        const char *cp;
+        char *end;
         STACK_OF(SSL_CIPHER) *sk;
         SSL_CIPHER *c;
+        size_t curlen = 0;
         int i;
 
         if ((s->session == NULL) || (s->session->ciphers == NULL) ||
                 (len < 2))
                 return(NULL);
 
-        p=buf;
         sk=s->session->ciphers;
+        buf[0] = '\0';
         for (i=0; i<sk_SSL_CIPHER_num(sk); i++)
                 {
-                /* Decrement for either the ':' or a '\0' */
-                len--;
                 c=sk_SSL_CIPHER_value(sk,i);
-                for (cp=c->name; *cp; )
+                end = buf + curlen;
+                if (strlcat(buf, c->name, len) >= len ||
+                    (curlen = strlcat(buf, ":", len)) >= len)
                         {
-                        if (len-- <= 0)
-                                {
-                                *p='\0';
-                                return(buf);
-                                }
-                        else
-                                *(p++)= *(cp++);
+                        /* remove truncated cipher from list */
+                        *end = '\0';
+                        break;
                         }
-                *(p++)=':';
                 }
-        p[-1]='\0';
+        /* remove trailing colon */
+        if ((end = strrchr(buf, ':')) != NULL)
+                *end = '\0';
         return(buf);
         }