From ae45175406f8dbda8cb77abcc9da5374c35a25ba Mon Sep 17 00:00:00 2001
From: Richard Levitte <levitte@openssl.org>
Date: Sun, 29 Jan 2017 08:52:02 +0100
Subject: Fix faulty free

On error, i2o_SCT_signature() and i2o_SCT() free a pointer that may
have wandered off from the start of the allocated block (not currently
true for i2o_SCT_signature(), but has that potential as the code may
change.  To avoid this, save away the start of the allocated block and
free that instead.

Thanks to Guido Vranken for reporting this issue.

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2323)
(cherry picked from commit d85d3c993e322d3e4c3f00be2910faa8c55b40e3)
---
 crypto/ct/ct_oct.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

(limited to 'crypto/ct')

diff --git a/crypto/ct/ct_oct.c b/crypto/ct/ct_oct.c
index d3edd39f5d..0dd691c0f7 100644
--- a/crypto/ct/ct_oct.c
+++ b/crypto/ct/ct_oct.c
@@ -153,7 +153,7 @@ err:
 int i2o_SCT_signature(const SCT *sct, unsigned char **out)
 {
     size_t len;
-    unsigned char *p = NULL;
+    unsigned char *p = NULL, *pstart = NULL;
 
     if (!SCT_signature_is_complete(sct)) {
         CTerr(CT_F_I2O_SCT_SIGNATURE, CT_R_SCT_INVALID_SIGNATURE);
@@ -177,7 +177,7 @@ int i2o_SCT_signature(const SCT *sct, unsigned char **out)
             p = *out;
             *out += len;
         } else {
-            p = OPENSSL_malloc(len);
+            pstart = p = OPENSSL_malloc(len);
             if (p == NULL) {
                 CTerr(CT_F_I2O_SCT_SIGNATURE, ERR_R_MALLOC_FAILURE);
                 goto err;
@@ -193,14 +193,14 @@ int i2o_SCT_signature(const SCT *sct, unsigned char **out)
 
     return len;
 err:
-    OPENSSL_free(p);
+    OPENSSL_free(pstart);
     return -1;
 }
 
 int i2o_SCT(const SCT *sct, unsigned char **out)
 {
     size_t len;
-    unsigned char *p = NULL;
+    unsigned char *p = NULL, *pstart = NULL;
 
     if (!SCT_is_complete(sct)) {
         CTerr(CT_F_I2O_SCT, CT_R_SCT_NOT_SET);
@@ -224,7 +224,7 @@ int i2o_SCT(const SCT *sct, unsigned char **out)
         p = *out;
         *out += len;
     } else {
-        p = OPENSSL_malloc(len);
+        pstart = p = OPENSSL_malloc(len);
         if (p == NULL) {
             CTerr(CT_F_I2O_SCT, ERR_R_MALLOC_FAILURE);
             goto err;
@@ -250,7 +250,7 @@ int i2o_SCT(const SCT *sct, unsigned char **out)
 
     return len;
 err:
-    OPENSSL_free(p);
+    OPENSSL_free(pstart);
     return -1;
 }
 
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