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| author | Prasad J Pandit <pjp@fedoraproject.org> | 2020-06-04 14:38:30 +0530 |
|---|---|---|
| committer | Gerd Hoffmann <kraxel@redhat.com> | 2020-06-05 09:14:40 +0200 |
| commit | a98610c429d52db0937c1e48659428929835c455 (patch) | |
| tree | a161aed3e9c0d0163faa5413db74f6f5ac7b60aa /hw/display | |
| parent | 66234fee9c2d37bfbc523aa8d0ae5300a14cc10e (diff) | |
| download | qemu-a98610c429d52db0937c1e48659428929835c455.zip qemu-a98610c429d52db0937c1e48659428929835c455.tar.gz qemu-a98610c429d52db0937c1e48659428929835c455.tar.bz2 | |
ati-vga: check mm_index before recursive call (CVE-2020-13800)
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>
Diffstat (limited to 'hw/display')
| -rw-r--r-- | hw/display/ati.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/hw/display/ati.c b/hw/display/ati.c index 065f197..67604e6 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: |