Check for PNG valid image before reading metadata

1 files changed, 9 insertions, 0 deletions

diff --git a/src/tuxpaint.c b/src/tuxpaint.c
index d9f98d1..6d271b3 100644
--- a/src/tuxpaint.c
+++ b/src/tuxpaint.c
@@ -19881,6 +19881,7 @@ void load_embedded_data(char *fname, SDL_Surface * org_surf)
   int ldelta, ldata, fgnd, bgnd;
   int num_unknowns = 0;
   SDL_Surface *aux_surf;
+  unsigned char png_sig[8];
 
   png_structp png_ptr;
   png_infop info_ptr;
@@ -19898,6 +19899,14 @@ void load_embedded_data(char *fname, SDL_Surface * org_surf)
     return;
   }
 
+  fread(png_sig, 1, sizeof(png_sig), fp);
+  if (png_sig_cmp(png_sig, 0, sizeof(png_sig)) != 0)
+  {
+    fprintf(stderr, "\nError: Wrong PNG image!\n%s\n\n", fname);
+    return;
+  }
+  fseek(fp, 0, SEEK_SET);
+
   png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
   if (png_ptr == NULL)
   {