Commit 52136026 authored by Gerd Hoffmann's avatar Gerd Hoffmann
Browse files

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: default avatar李强 <liqiang6-s@360.cn>
Signed-off-by: default avatarGerd Hoffmann <kraxel@redhat.com>
Message-id: 1464592161-18348-2-git-send-email-kraxel@redhat.com
parent fa06e5cb

hw/display/vmware_vga.c

+15 −13
Original line number Diff line number Diff line
@@ -555,6 +555,21 @@ static inline int vmsvga_fifo_length(struct vmsvga_state_s *s) 
    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 @@ static void vmsvga_value_write(void *opaque, uint32_t address, uint32_t value) 
    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;