[dunfell,v2] qemu: backport patch fix for CVE-2020-13791

Upstream patch:
https://lists.gnu.org/archive/html/qemu-devel/2020-06/msg00979.html

CVE: CVE-2020-13791

Update v2: rebase with patch for CVE-2020-13253 and
add Upstream-Status in patch description

Signed-off-by: Davide Gardenal <davide.gardenal@huawei.com>
---
 meta/recipes-devtools/qemu/qemu.inc           |  1 +
 .../qemu/qemu/CVE-2020-13791.patch            | 44 +++++++++++++++++++
 2 files changed, 45 insertions(+)
 create mode 100644 meta/recipes-devtools/qemu/qemu/CVE-2020-13791.patch

On Thu, Mar 24, 2022 at 1:32 AM Davide Gardenal
<davidegarde2000@gmail.com> wrote:
>
> Upstream patch:
> https://lists.gnu.org/archive/html/qemu-devel/2020-06/msg00979.html
>
> CVE: CVE-2020-13791
>
> Update v2: rebase with patch for CVE-2020-13253 and
> add Upstream-Status in patch description

Thanks for sending v2

In the future if you put the above version change note after the three
dashes below it will make life just a little bit easier for me.

When it is prior to the dashes I have to hand edit the patch to remove
the version notes, otherwise they will end up in the commit message.

No big deal either way, I appreciate the help with CVEs!

>
> Signed-off-by: Davide Gardenal <davide.gardenal@huawei.com>
> ---

i.e. put version notes here!

>  meta/recipes-devtools/qemu/qemu.inc           |  1 +
>  .../qemu/qemu/CVE-2020-13791.patch            | 44 +++++++++++++++++++
>  2 files changed, 45 insertions(+)
>  create mode 100644 meta/recipes-devtools/qemu/qemu/CVE-2020-13791.patch
>
> diff --git a/meta/recipes-devtools/qemu/qemu.inc b/meta/recipes-devtools/qemu/qemu.inc
> index 0bdc917783..25c2cdef3a 100644
> --- a/meta/recipes-devtools/qemu/qemu.inc
> +++ b/meta/recipes-devtools/qemu/qemu.inc
> @@ -97,6 +97,7 @@ SRC_URI = "https://download.qemu.org/${BPN}-${PV}.tar.xz \
>             file://CVE-2020-13253_3.patch \
>             file://CVE-2020-13253_4.patch \
>             file://CVE-2020-13253_5.patch \
> +           file://CVE-2020-13791.patch \
>             "
>  UPSTREAM_CHECK_REGEX = "qemu-(?P<pver>\d+(\.\d+)+)\.tar"
>
> diff --git a/meta/recipes-devtools/qemu/qemu/CVE-2020-13791.patch b/meta/recipes-devtools/qemu/qemu/CVE-2020-13791.patch
> new file mode 100644
> index 0000000000..1e8278f7b7
> --- /dev/null
> +++ b/meta/recipes-devtools/qemu/qemu/CVE-2020-13791.patch
> @@ -0,0 +1,44 @@
> +Date:  Thu, 4 Jun 2020 16:25:24 +0530
> +From: Prasad J Pandit <pjp@fedoraproject.org>
> +Subject:       [PATCH v3] ati-vga: check address before reading configuration bytes (CVE-2020-13791)
> +
> +While reading PCI configuration bytes, a guest may send an
> +address towards the end of the configuration space. It may lead
> +to an OOB access issue. Add check to ensure 'address + size' is
> +within PCI configuration space.
> +
> +CVE: CVE-2020-13791
> +
> +Upstream-Status: Submitted
> +https://lists.gnu.org/archive/html/qemu-devel/2020-06/msg00979.html
> +
> +Reported-by: Ren Ding <rding@gatech.edu>
> +Reported-by: Hanqing Zhao <hanqing@gatech.edu>
> +Reported-by: Yi Ren <c4tren@gmail.com>
> +Suggested-by: BALATON Zoltan <balaton@eik.bme.hu>
> +Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
> +Signed-off-by: Davide Gardenal <davide.gardenal@huawei.com>
> +---
> + hw/display/ati.c | 4 +++-
> + 1 file changed, 3 insertions(+), 1 deletion(-)
> +
> +Update v3: avoid modifying 'addr' variable
> +  -> https://lists.gnu.org/archive/html/qemu-devel/2020-06/msg00834.html
> +
> +diff --git a/hw/display/ati.c b/hw/display/ati.c
> +index 67604e68de..b4d0fd88b7 100644
> +--- a/hw/display/ati.c
> ++++ b/hw/display/ati.c
> +@@ -387,7 +387,9 @@ static uint64_t ati_mm_read(void *opaque, hwaddr addr, unsigned int size)
> +         val = s->regs.crtc_pitch;
> +         break;
> +     case 0xf00 ... 0xfff:
> +-        val = pci_default_read_config(&s->dev, addr - 0xf00, size);
> ++        if ((addr - 0xf00) + size <= pci_config_size(&s->dev)) {
> ++            val = pci_default_read_config(&s->dev, addr - 0xf00, size);
> ++        }
> +         break;
> +     case CUR_OFFSET:
> +         val = s->regs.cur_offset;
> +--
> +2.26.2
> --
> 2.32.0
>
>
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Understood, sorry I'm not yet very familiar, still learning.

Thanks for the feedback!