render/gles2: check buffer stride when uploading texture

If the stride is too small, the driver could end up segfaulting
(e.g. radeonsi segfaults in __memmove_sse2_unaligned_erms).

render/gles2/texture.c

@@ -30,6 +30,21 @@ static bool gles2_texture_is_opaque(struct wlr_texture *wlr_texture) {
 	return !texture->has_alpha;
 }
 
+static bool check_stride(const struct wlr_gles2_pixel_format *fmt,
+		uint32_t stride, uint32_t width) {
+	if (stride % (fmt->bpp / 8) != 0) {
+		wlr_log(WLR_ERROR, "Invalid stride %d (incompatible with %d "
+			"bytes-per-pixel)", stride, fmt->bpp / 8);
+		return false;
+	}
+	if (stride < width * (fmt->bpp / 8)) {
+		wlr_log(WLR_ERROR, "Invalid stride %d (too small for %d "
+			"bytes-per-pixel and width %d)", stride, fmt->bpp / 8, width);
+		return false;
+	}
+	return true;
+}
+
 static bool gles2_texture_write_pixels(struct wlr_texture *wlr_texture,
 		uint32_t stride, uint32_t width, uint32_t height,
 		uint32_t src_x, uint32_t src_y, uint32_t dst_x, uint32_t dst_y,
@@ -45,6 +60,10 @@ static bool gles2_texture_write_pixels(struct wlr_texture *wlr_texture,
 		get_gles2_format_from_wl(texture->wl_format);
 	assert(fmt);
 
+	if (!check_stride(fmt, stride, width)) {
+		return false;
+	}
+
 	struct wlr_egl_context prev_ctx;
 	wlr_egl_save_context(&prev_ctx);
 	wlr_egl_make_current(texture->renderer->egl);
@@ -142,6 +161,10 @@ struct wlr_texture *gles2_texture_from_pixels(struct wlr_renderer *wlr_renderer,
 		return NULL;
 	}
 
+	if (!check_stride(fmt, stride, width)) {
+		return NULL;
+	}
+
 	struct wlr_gles2_texture *texture =
 		calloc(1, sizeof(struct wlr_gles2_texture));
 	if (texture == NULL) {