vmsvga: move fifo sanity checks to vmsvga_fifo_length
Sanity checks are applied when the fifo is enabled by the guest
(SVGA_REG_CONFIG_DONE write). Which doesn't help much if the guest
changes the fifo registers afterwards. Move the checks to
vmsvga_fifo_length so they are done each time qemu is about to read
from the fifo.
Fixes: CVE-2016-4454
Cc: qemu-stable@nongnu.org
Cc: P J P <ppandit@redhat.com>
Reported-by: 李强 <liqiang6-s@360.cn>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-id: 1464592161-18348-2-git-send-email-kraxel@redhat.com
diff --git a/hw/display/vmware_vga.c b/hw/display/vmware_vga.c
index 0c63fa8..63a7c05 100644
--- a/hw/display/vmware_vga.c
+++ b/hw/display/vmware_vga.c
@@ -555,6 +555,21 @@
if (!s->config || !s->enable) {
return 0;
}
+
+ /* Check range and alignment. */
+ if ((CMD(min) | CMD(max) | CMD(next_cmd) | CMD(stop)) & 3) {
+ return 0;
+ }
+ if (CMD(min) < (uint8_t *) s->cmd->fifo - (uint8_t *) s->fifo) {
+ return 0;
+ }
+ if (CMD(max) > SVGA_FIFO_SIZE) {
+ return 0;
+ }
+ if (CMD(max) < CMD(min) + 10 * 1024) {
+ return 0;
+ }
+
num = CMD(next_cmd) - CMD(stop);
if (num < 0) {
num += CMD(max) - CMD(min);
@@ -1005,19 +1020,6 @@
case SVGA_REG_CONFIG_DONE:
if (value) {
s->fifo = (uint32_t *) s->fifo_ptr;
- /* Check range and alignment. */
- if ((CMD(min) | CMD(max) | CMD(next_cmd) | CMD(stop)) & 3) {
- break;
- }
- if (CMD(min) < (uint8_t *) s->cmd->fifo - (uint8_t *) s->fifo) {
- break;
- }
- if (CMD(max) > SVGA_FIFO_SIZE) {
- break;
- }
- if (CMD(max) < CMD(min) + 10 * 1024) {
- break;
- }
vga_dirty_log_stop(&s->vga);
}
s->config = !!value;
