| From a98610c429d52db0937c1e48659428929835c455 Mon Sep 17 00:00:00 2001 |
| From: Prasad J Pandit <pjp@fedoraproject.org> |
| Date: Thu, 4 Jun 2020 14:38:30 +0530 |
| Subject: [PATCH] ati-vga: check mm_index before recursive call |
| (CVE-2020-13800) |
| MIME-Version: 1.0 |
| Content-Type: text/plain; charset=UTF-8 |
| Content-Transfer-Encoding: 8bit |
| |
| While accessing VGA registers via ati_mm_read/write routines, |
| a guest may set 's->regs.mm_index' such that it leads to infinite |
| recursion. Check mm_index value to avoid such recursion. Log an |
| error message for wrong values. |
| |
| Reported-by: Ren Ding <rding@gatech.edu> |
| Reported-by: Hanqing Zhao <hanqing@gatech.edu> |
| Reported-by: Yi Ren <c4tren@gmail.com> |
| Message-id: 20200604090830.33885-1-ppandit@redhat.com |
| Suggested-by: BALATON Zoltan <balaton@eik.bme.hu> |
| Suggested-by: Philippe Mathieu-Daudé <philmd@redhat.com> |
| Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org> |
| Signed-off-by: Gerd Hoffmann <kraxel@redhat.com> |
| |
| Upstream-Status: Backport [a98610c429d52db0937c1e48659428929835c455] |
| CVE: CVE-2020-13800 |
| Signed-off-by: Sakib Sajal <sakib.sajal@windriver.com> |
| --- |
| hw/display/ati.c | 10 ++++++++-- |
| 1 file changed, 8 insertions(+), 2 deletions(-) |
| |
| diff --git a/hw/display/ati.c b/hw/display/ati.c |
| index 065f197678..67604e68de 100644 |
| --- a/hw/display/ati.c |
| +++ b/hw/display/ati.c |
| @@ -285,8 +285,11 @@ static uint64_t ati_mm_read(void *opaque, hwaddr addr, unsigned int size) |
| if (idx <= s->vga.vram_size - size) { |
| val = ldn_le_p(s->vga.vram_ptr + idx, size); |
| } |
| - } else { |
| + } else if (s->regs.mm_index > MM_DATA + 3) { |
| val = ati_mm_read(s, s->regs.mm_index + addr - MM_DATA, size); |
| + } else { |
| + qemu_log_mask(LOG_GUEST_ERROR, |
| + "ati_mm_read: mm_index too small: %u\n", s->regs.mm_index); |
| } |
| break; |
| case BIOS_0_SCRATCH ... BUS_CNTL - 1: |
| @@ -520,8 +523,11 @@ static void ati_mm_write(void *opaque, hwaddr addr, |
| if (idx <= s->vga.vram_size - size) { |
| stn_le_p(s->vga.vram_ptr + idx, size, data); |
| } |
| - } else { |
| + } else if (s->regs.mm_index > MM_DATA + 3) { |
| ati_mm_write(s, s->regs.mm_index + addr - MM_DATA, data, size); |
| + } else { |
| + qemu_log_mask(LOG_GUEST_ERROR, |
| + "ati_mm_write: mm_index too small: %u\n", s->regs.mm_index); |
| } |
| break; |
| case BIOS_0_SCRATCH ... BUS_CNTL - 1: |
| -- |
| 2.20.1 |
| |