Perform range checking on app supplied texture base level

It is possible for applications to specify any texture base level,
including trivially invalid values (i.e., 47000000).  When an app
specifies an invalide base level, we should gracefully disable the
texture instead of accessing memory outside the gl_texture_object.

This fixes an occasional segfault in one of our conformance tests.

diff --git a/src/mesa/main/texobj.c b/src/mesa/main/texobj.c
index 2a54ff7..d8e8b55 100644 (file)
--- a/src/mesa/main/texobj.c
+++ b/src/mesa/main/texobj.c
@@ -383,6 +383,18 @@ _mesa_test_texobj_completeness( const GLcontext *ctx,
 
    t->_Complete = GL_TRUE;  /* be optimistic */
 
+   /* Detect cases where the application set the base level to an invalid
+    * value.
+    */
+   if ((baseLevel < 0) || (baseLevel > MAX_TEXTURE_LEVELS)) {
+      char s[100];
+      _mesa_sprintf(s, "obj %p (%d) base level = %d is invalid",
+              (void *) t, t->Name, baseLevel);
+      incomplete(t, s);
+      t->_Complete = GL_FALSE;
+      return;
+   }
+
    /* Always need the base level image */
    if (!t->Image[0][baseLevel]) {
       char s[100];