[PATCH] SiS DRM: Fix possible NULL dereference

This fixes a NULL pointer reference in DRM. The SiS driver tries to
allocate a big chunk of memory, but the return value is never checked.

Reported in Novell bugzilla #132271:
https://bugzilla.novell.com/show_bug.cgi?id=132271

Signed-off-by: Takashi Iwai <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/char/drm/drm_context.c

···
 
 	if (ctx.handle != DRM_KERNEL_CONTEXT) {
 		if (dev->driver->context_ctor)
-			dev->driver->context_ctor(dev, ctx.handle);
+			if (!dev->driver->context_ctor(dev, ctx.handle)) {
+				DRM_DEBUG( "Running out of ctxs or memory.\n");
+				return -ENOMEM;
+			}
 	}
 
 	ctx_entry = drm_alloc(sizeof(*ctx_entry), DRM_MEM_CTXLIST);