[gdk-pixbuf] tiff: Avoid overflowing buffer size computation

[Bastien Nocera <hadess src gnome org>]

commit 1e513abdb55529f888233d3c96b27352d83aad5f
Author: Bastien Nocera <hadess hadess net>
Date:   Tue Dec 5 10:26:49 2017 +0100

    tiff: Avoid overflowing buffer size computation
    
    Use g_uint_checked_mul() to avoid overflowing the guint used for buffer
    size calculation.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=779020

 gdk-pixbuf/io-tiff.c |   11 +++++++++--
 1 files changed, 9 insertions(+), 2 deletions(-)
---
diff --git a/gdk-pixbuf/io-tiff.c b/gdk-pixbuf/io-tiff.c
index 7ca0a56..49fe60e 100644
--- a/gdk-pixbuf/io-tiff.c
+++ b/gdk-pixbuf/io-tiff.c
@@ -529,8 +529,15 @@ make_available_at_least (TiffContext *context, guint needed)
         need_alloc = context->used + needed;
         if (need_alloc > context->allocated) {
                 guint new_size = 1;
-                while (new_size < need_alloc)
-                        new_size *= 2;
+                while (new_size < need_alloc) {
+                        if (!g_uint_checked_mul (&new_size, new_size, 2)) {
+                                new_size = 0;
+                                break;
+                        }
+                }
+
+                if (new_size == 0)
+                        return FALSE;
 
                 new_buffer = g_try_realloc (context->buffer, new_size);
                 if (new_buffer) {