fix(ico): More robust to corrupted ICO files (#4625)

Signed-off-by: Larry Gritz <[email protected]>

Author: lgritz

src/ico.imageio/icoinput.cpp

@@ -190,6 +190,19 @@ ICOInput::seek_subimage(int subimage, int miplevel)
         swap_endian(&subimg.numColours);
     }
 
+    // some sanity checking
+    if (subimg.bpp != 1 && subimg.bpp != 4 && subimg.bpp != 8
+        && subimg.bpp != 16 && subimg.bpp != 24 && subimg.bpp != 32) {
+        errorfmt("Unsupported image color depth, probably corrupt file");
+        return false;
+    }
+    if (subimg.reserved != 0) {
+        errorfmt(
+            "Probably corrupt file (clue: header 'reserved' value should always be 0)",
+            subimg.reserved);
+        return false;
+    }
+
     ioseek(subimg.ofs, SEEK_SET);
 
     // test for a PNG icon

testsuite/ico/ref/out.txt

@@ -45,3 +45,4 @@ Reading ../oiio-images/ico/oiio.ico
     oiio:BitsPerSample: 8
 Comparing "../oiio-images/ico/oiio.ico" and "oiio.ico"
 PASS
+iconvert ERROR: Unsupported image color depth, probably corrupt file

testsuite/ico/run.py

@@ -4,4 +4,9 @@
 # SPDX-License-Identifier: Apache-2.0
 # https://github.com/AcademySoftwareFoundation/OpenImageIO
 
-command = rw_command (OIIO_TESTSUITE_IMAGEDIR, "oiio.ico")
+failureok = 1
+redirect = ' >> out.txt 2>&1 '
+
+command += rw_command (OIIO_TESTSUITE_IMAGEDIR, "oiio.ico")
+command += run_app (oiio_app("iconvert") + " src/bad1.ico out.tif")
+