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qemu: fix CVE-2021-20196

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(From OE-Core rev: 3014cb660e7128f65ee2aec004ede39e80cd891d)

Signed-off-by: Sakib Sajal <sakib.sajal@windriver.com>
Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
This commit is contained in:
Sakib Sajal
2022-02-02 10:47:20 -05:00
committed by Richard Purdie
parent 83e7e63458
commit b1bb20b5c0
3 changed files with 123 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
meta/recipes-devtools/qemu/qemu.inc
View File

@@ -73,6 +73,8 @@ SRC_URI = "https://download.qemu.org/${BPN}-${PV}.tar.xz \
file://CVE-2021-3713.patch \
file://CVE-2021-3748.patch \
file://CVE-2021-3930.patch \
file://CVE-2021-20196_1.patch \
file://CVE-2021-20196_2.patch \
"
UPSTREAM_CHECK_REGEX = "qemu-(?P<pver>\d+(\.\d+)+)\.tar"

54
meta/recipes-devtools/qemu/qemu/CVE-2021-20196_1.patch Normal file
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@@ -0,0 +1,54 @@
From e907ff3d4cb7fd20d402f45355059e67d0dc93e7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= <philmd@redhat.com>
Date: Wed, 24 Nov 2021 17:15:34 +0100
Subject: [PATCH 11/12] hw/block/fdc: Extract blk_create_empty_drive()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
We are going to re-use this code in the next commit,
so extract it as a new blk_create_empty_drive() function.
Inspired-by: Hanna Reitz <hreitz@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20211124161536.631563-2-philmd@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
Upstream-Status: Backport [b154791e7b6d4ca5cdcd54443484d97360bd7ad2]
CVE: CVE-2021-20196
Signed-off-by: Sakib Sajal <sakib.sajal@windriver.com>
---
hw/block/fdc.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/hw/block/fdc.c b/hw/block/fdc.c
index 4c2c35e22..854b4f172 100644
--- a/hw/block/fdc.c
+++ b/hw/block/fdc.c
@@ -61,6 +61,12 @@
} while (0)
+/* Anonymous BlockBackend for empty drive */
+static BlockBackend *blk_create_empty_drive(void)
+{
+ return blk_new(qemu_get_aio_context(), 0, BLK_PERM_ALL);
+}
+
/********************************************************/
/* qdev floppy bus */
@@ -543,8 +549,7 @@ static void floppy_drive_realize(DeviceState *qdev, Error **errp)
}
if (!dev->conf.blk) {
- /* Anonymous BlockBackend for an empty drive */
- dev->conf.blk = blk_new(qemu_get_aio_context(), 0, BLK_PERM_ALL);
+ dev->conf.blk = blk_create_empty_drive();
ret = blk_attach_dev(dev->conf.blk, qdev);
assert(ret == 0);
--
2.31.1

67
meta/recipes-devtools/qemu/qemu/CVE-2021-20196_2.patch Normal file
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@@ -0,0 +1,67 @@
From 1d48445a951fd5504190a38abeda70ea9372cf77 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= <philmd@redhat.com>
Date: Wed, 24 Nov 2021 17:15:35 +0100
Subject: [PATCH 12/12] hw/block/fdc: Kludge missing floppy drive to fix
CVE-2021-20196
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Guest might select another drive on the bus by setting the
DRIVE_SEL bit of the DIGITAL OUTPUT REGISTER (DOR).
The current controller model doesn't expect a BlockBackend
to be NULL. A simple way to fix CVE-2021-20196 is to create
an empty BlockBackend when it is missing. All further
accesses will be safely handled, and the controller state
machines keep behaving correctly.
Cc: qemu-stable@nongnu.org
Fixes: CVE-2021-20196
Reported-by: Gaoning Pan (Ant Security Light-Year Lab) <pgn@zju.edu.cn>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20211124161536.631563-3-philmd@redhat.com
BugLink: https://bugs.launchpad.net/qemu/+bug/1912780
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/338
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>
Upstream-Status: Backport [1ab95af033a419e7a64e2d58e67dd96b20af5233]
CVE: CVE-2021-20196
Signed-off-by: Sakib Sajal <sakib.sajal@windriver.com>
---
hw/block/fdc.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/hw/block/fdc.c b/hw/block/fdc.c
index 854b4f172..a736c4d14 100644
--- a/hw/block/fdc.c
+++ b/hw/block/fdc.c
@@ -1365,7 +1365,19 @@ static FDrive *get_drv(FDCtrl *fdctrl, int unit)
static FDrive *get_cur_drv(FDCtrl *fdctrl)
{
- return get_drv(fdctrl, fdctrl->cur_drv);
+ FDrive *cur_drv = get_drv(fdctrl, fdctrl->cur_drv);
+
+ if (!cur_drv->blk) {
+ /*
+ * Kludge: empty drive line selected. Create an anonymous
+ * BlockBackend to avoid NULL deref with various BlockBackend
+ * API calls within this model (CVE-2021-20196).
+ * Due to the controller QOM model limitations, we don't
+ * attach the created to the controller device.
+ */
+ cur_drv->blk = blk_create_empty_drive();
+ }
+ return cur_drv;
}
/* Status A register : 0x00 (read-only) */
--
2.31.1