[openssl-commits] [openssl] OpenSSL_1_0_2-stable update

[Matt Caswell]

The branch OpenSSL_1_0_2-stable has been updated
       via  6a6213556a80ab0a9eb926a1d6023b8bf44f2afd (commit)
      from  6fe43af8d77b119f8af913c284149bca482ee58c (commit)


- Log -----------------------------------------------------------------
commit 6a6213556a80ab0a9eb926a1d6023b8bf44f2afd
Author: Matt Caswell <matt at openssl.org>
Date:   Fri Mar 10 10:51:35 2017 +0000

    Fix out-of-memory condition in conf
    
    conf has the ability to expand variables in config files. Repeatedly doing
    this can lead to an exponential increase in the amount of memory required.
    This places a limit on the length of a value that can result from an
    expansion.
    
    Credit to OSS-Fuzz for finding this problem.
    
    Reviewed-by: Rich Salz <rsalz at openssl.org>
    Reviewed-by: Richard Levitte <levitte at openssl.org>
    (Merged from https://github.com/openssl/openssl/pull/2894)
    (cherry picked from commit 8a585601fea1091022034dd14b961c1ecd5916c3)

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

Summary of changes:
 crypto/conf/conf.h     |  1 +
 crypto/conf/conf_def.c | 16 ++++++++++++++--
 crypto/conf/conf_err.c |  2 ++
 doc/apps/config.pod    |  3 ++-
 4 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/crypto/conf/conf.h b/crypto/conf/conf.h
index 8d926d5..fe49113 100644
--- a/crypto/conf/conf.h
+++ b/crypto/conf/conf.h
@@ -259,6 +259,7 @@ void ERR_load_CONF_strings(void);
 # define CONF_R_NO_VALUE                                  108
 # define CONF_R_UNABLE_TO_CREATE_NEW_SECTION              103
 # define CONF_R_UNKNOWN_MODULE_NAME                       113
+# define CONF_R_VARIABLE_EXPANSION_TOO_LONG               116
 # define CONF_R_VARIABLE_HAS_NO_VALUE                     104
 
 #ifdef  __cplusplus
diff --git a/crypto/conf/conf_def.c b/crypto/conf/conf_def.c
index 68c77ce..75e309a 100644
--- a/crypto/conf/conf_def.c
+++ b/crypto/conf/conf_def.c
@@ -69,6 +69,12 @@
 #include <openssl/buffer.h>
 #include <openssl/err.h>
 
+/*
+ * The maximum length we can grow a value to after variable expansion. 64k
+ * should be more than enough for all reasonable uses.
+ */
+#define MAX_CONF_VALUE_LENGTH       65536
+
 static char *eat_ws(CONF *conf, char *p);
 static char *eat_alpha_numeric(CONF *conf, char *p);
 static void clear_comments(CONF *conf, char *p);
@@ -530,6 +536,8 @@ static int str_copy(CONF *conf, char *section, char **pto, char *from)
         } else if (IS_EOF(conf, *from))
             break;
         else if (*from == '$') {
+            size_t newsize;
+
             /* try to expand it */
             rrp = NULL;
             s = &(from[1]);
@@ -584,8 +592,12 @@ static int str_copy(CONF *conf, char *section, char **pto, char *from)
                 CONFerr(CONF_F_STR_COPY, CONF_R_VARIABLE_HAS_NO_VALUE);
                 goto err;
             }
-            if (!BUF_MEM_grow_clean(buf,
-                        (strlen(p) + buf->length - (e - from)))) {
+            newsize = strlen(p) + buf->length - (e - from);
+            if (newsize > MAX_CONF_VALUE_LENGTH) {
+                CONFerr(CONF_F_STR_COPY, CONF_R_VARIABLE_EXPANSION_TOO_LONG);
+                goto err;
+            }
+            if (!BUF_MEM_grow_clean(buf, newsize)) {
                 CONFerr(CONF_F_STR_COPY, ERR_R_MALLOC_FAILURE);
                 goto err;
             }
diff --git a/crypto/conf/conf_err.c b/crypto/conf/conf_err.c
index bb5e2fe..b0b6896 100644
--- a/crypto/conf/conf_err.c
+++ b/crypto/conf/conf_err.c
@@ -115,6 +115,8 @@ static ERR_STRING_DATA CONF_str_reasons[] = {
     {ERR_REASON(CONF_R_UNABLE_TO_CREATE_NEW_SECTION),
      "unable to create new section"},
     {ERR_REASON(CONF_R_UNKNOWN_MODULE_NAME), "unknown module name"},
+    {ERR_REASON(CONF_R_VARIABLE_EXPANSION_TOO_LONG),
+     "variable expansion too long"},
     {ERR_REASON(CONF_R_VARIABLE_HAS_NO_VALUE), "variable has no value"},
     {0, NULL}
 };
diff --git a/doc/apps/config.pod b/doc/apps/config.pod
index e125915..3f607d3 100644
--- a/doc/apps/config.pod
+++ b/doc/apps/config.pod
@@ -47,7 +47,8 @@ or B<${section::name}>. By using the form B<$ENV::name> environment
 variables can be substituted. It is also possible to assign values to
 environment variables by using the name B<ENV::name>, this will work
 if the program looks up environment variables using the B<CONF> library
-instead of calling B<getenv()> directly.
+instead of calling B<getenv()> directly. The value string must not exceed 64k in
+length after variable expansion. Otherwise an error will occur.
 
 It is possible to escape certain characters by using any kind of quote
 or the B<\> character. By making the last character of a line a B<\>