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From 13de299b112a59c373b330f0539166ecc9a7627b Mon Sep 17 00:00:00 2001
From: Daniel Stenberg <daniel@haxx.se>
Date: Tue, 3 Sep 2019 22:59:32 +0200
Subject: [PATCH] security:read_data fix bad realloc()

... that could end up a double-free

CVE-2019-5481
Bug: https://curl.haxx.se/docs/CVE-2019-5481.html

Upstream-commit: 9069838b30fb3b48af0123e39f664cea683254a5
Signed-off-by: Kamil Dudka <kdudka@redhat.com>
---
 lib/security.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/lib/security.c b/lib/security.c
index 550ea2d..c5e4e13 100644
--- a/lib/security.c
+++ b/lib/security.c
@@ -191,7 +191,6 @@ static CURLcode read_data(struct connectdata *conn,
                           struct krb5buffer *buf)
 {
   int len;
-  void *tmp = NULL;
   CURLcode result;
 
   result = socket_read(fd, &len, sizeof(len));
@@ -201,12 +200,11 @@ static CURLcode read_data(struct connectdata *conn,
   if(len) {
     /* only realloc if there was a length */
     len = ntohl(len);
-    tmp = Curl_saferealloc(buf->data, len);
+    buf->data = Curl_saferealloc(buf->data, len);
   }
-  if(tmp == NULL)
+  if(!len || !buf->data)
     return CURLE_OUT_OF_MEMORY;
 
-  buf->data = tmp;
   result = socket_read(fd, buf->data, len);
   if(result)
     return result;
-- 
2.20.1