Fix potential random malloc in pem_read()

3 files changed, 10 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 0f8d4b8..d584090 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -11,6 +11,10 @@ Security
      but might be in other uses. On 32 bit machines, requires reading a string
      of close to or larger than 1GB to exploit; on 64 bit machines, would require
      reading a string of close to or larger than 2^62 bytes.
+   * Fix potential random memory allocation in mbedtls_pem_read_buffer()
+     on crafted PEM input data. Found an fix provided by Guid Vranken.
+     Not triggerable remotely in TLS. Triggerable remotely if you accept PEM
+     data from an untrusted source.
 
 = Version 1.2.16 released 2015-09-17
 
diff --git a/library/base64.c b/library/base64.c
index c94995b..dba4c23 100644
--- a/library/base64.c
+++ b/library/base64.c
@@ -176,7 +176,10 @@ int base64_decode( unsigned char *dst, size_t *dlen,
     }
 
     if( n == 0 )
+    {
+        *dlen = 0;
         return( 0 );
+    }
 
     n = ((n * 6) + 7) >> 3;
     n -= j;
diff --git a/library/pem.c b/library/pem.c
index 5c973ac..81098ee 100644
--- a/library/pem.c
+++ b/library/pem.c
@@ -287,6 +287,9 @@ int pem_read_buffer( pem_context *ctx, char *header, char *footer, const unsigne
 #endif /* POLARSSL_MD5_C && (POLARSSL_AES_C || POLARSSL_DES_C) */
     }
 
+    if( s1 == s2 )
+        return( POLARSSL_ERR_PEM_INVALID_DATA );
+
     len = 0;
     ret = base64_decode( NULL, &len, s1, s2 - s1 );