(__argp_fmtstream_ensure): Check for size_t overflow when reallocating storage.

diff --git a/argp/argp-fmtstream.c b/argp/argp-fmtstream.c
index d06ea84..215160b 100644 (file)
--- a/argp/argp-fmtstream.c
+++ b/argp/argp-fmtstream.c
@@ -385,10 +385,11 @@ __argp_fmtstream_ensure (struct argp_fmtstream *fs, size_t amount)
       if ((size_t) (fs->end - fs->buf) < amount)
        /* Gotta grow the buffer.  */
        {
-         size_t new_size = fs->end - fs->buf + amount;
-         char *new_buf = realloc (fs->buf, new_size);
+         size_t old_size = fs->end - fs->buf;
+         size_t new_size = old_size + amount;
+         char *new_buf;
 
-         if (! new_buf)
+         if (new_size < old_size || ! (new_buf = realloc (fs->buf, new_size)))
            {
              __set_errno (ENOMEM);
              return 0;