From 31106a073882656a2a5ab56c4ce2847e9a334c3c Mon Sep 17 00:00:00 2001

From: Daniel Stenberg <[email protected]>

Date: Wed, 28 Sep 2016 10:15:34 +0200

Subject: [PATCH] aprintf: detect wrap-around when growing allocation

On 32bit systems we could otherwise wrap around after 2GB and allocate 0

bytes and crash.

CVE-2016-8618

Bug: https://curl.haxx.se/docs/adv_20161102D.html

Reported-by: Cure53

---

 lib/mprintf.c | 9 ++++++---

 1 file changed, 6 insertions(+), 3 deletions(-)

--- lib/mprintf.c

+++ lib/mprintf.c

@@ -1034,20 +1034,23 @@ static int alloc_addbyter(int output, FILE *data)

     }

     infop->alloc = 32;

     infop->len =0;

   }

   else if(infop->len+1 >= infop->alloc) {

-    char *newptr;

+    char *newptr = NULL;

+    size_t newsize = infop->alloc*2;

-    newptr = realloc(infop->buffer, infop->alloc*2);

+    /* detect wrap-around or other overflow problems */

+    if(newsize > infop->alloc)

+      newptr = realloc(infop->buffer, newsize);

     if(!newptr) {

       infop->fail = 1;

       return -1; /* fail */

     }

     infop->buffer = newptr;

-    infop->alloc *= 2;

+    infop->alloc = newsize;

   }

   infop->buffer[ infop->len ] = outc;

   infop->len++;

-- 

2.9.3