INN commit: branches/2.4/nnrpd (tls.c)

[INN Commit]

    Date: Saturday, May 24, 2008 @ 08:13:03
  Author: iulius
Revision: 7844

When an article of a size greater than remaining stack is retrieved via 
SSL, a segmentation fault will occur due to the use of alloca().
The below patch uses heap based realloc() instead of stack based alloca(), 
with a static buffer growing as needed.
It uses realloc() instead of malloc() for performance reasons since this 
function is called frequently.  The caveat is that the memory is never 
free()'ed, so if more correct code is desired, it should be adjusted.

Thanks to Chris Caputo for this patch.

Modified:
  branches/2.4/nnrpd/tls.c

-------+
 tls.c |   44 ++++++++++----------------------------------
 1 file changed, 10 insertions(+), 34 deletions(-)

Modified: tls.c
===================================================================
--- tls.c	2008-05-23 22:06:00 UTC (rev 7843)
+++ tls.c	2008-05-24 15:13:03 UTC (rev 7844)
@@ -32,39 +32,8 @@
 #include <sys/stat.h>
 #include <sys/uio.h>
 
-/* taken from lib/parsedate.c */
-#ifndef WRITEV_USE_ALLOCA
-#ifdef alloca
-#define WRITEV_USE_ALLOCA
-#else /* alloca not defined */
-#ifdef __GNUC__
-#define WRITEV_USE_ALLOCA
-#define alloca __builtin_alloca
-#else /* not GNU C.  */
-#if (!defined (__STDC__) && defined (sparc)) || defined (__sparc__) || defined (__sparc) || defined (__sgi) || (defined (__sun) && defined (__i386))
-#define WRITEV_USE_ALLOCA
-#include <alloca.h>
-#else /* not sparc */
-#if (defined (_MSDOS) || defined (_MSDOS_)) && !defined (__TURBOC__)
-#else /* not MSDOS, or __TURBOC__ */
-#if defined(_AIX)
- #pragma alloca
-#define WRITEV_USE_ALLOCA
-#endif /* not _AIX */
-#endif /* not MSDOS, or __TURBOC__ */
-#endif /* not sparc */
-#endif /* not GNU C */
-#endif /* alloca not defined */
-#endif /* WRITEV_USE_ALLOCA not defined */
-#ifdef WRITEV_USE_ALLOCA
-#define WRITEV_ALLOC alloca
-#else
-#define WRITEV_ALLOC malloc
 #endif
 
-
-#endif
-
 /* outside the ifdef so `make depend` works even ifndef HAVE_SSL */
 #include "tls.h"
 #include "sasl_config.h"
@@ -707,7 +676,8 @@
      const struct iovec *vector;
      int count;
 {
-  char *buffer;
+  static char *buffer = NULL;
+  static size_t allocsize = 0;
   char *bp;
   size_t bytes, to_copy;
   int i;
@@ -715,8 +685,14 @@
   bytes = 0;
   for (i = 0; i < count; ++i)
     bytes += vector[i].iov_len;
-  /* Allocate a temporary buffer to hold the data.  */
-  buffer = (char *) WRITEV_ALLOC (bytes);
+  /* Allocate a buffer to hold the data.  */
+  if (NULL == buffer) {
+    buffer = (char *) xmalloc(bytes);
+    allocsize = bytes;
+  } else if (bytes > allocsize) {
+    buffer = (char *) xrealloc (buffer, bytes);
+    allocsize = bytes;
+  }
   /* Copy the data into BUFFER.  */
   to_copy = bytes;
   bp = buffer;