qemu: fix CVE-2023-42467

QEMU through 8.0.0 could trigger a division by zero in scsi_disk_reset
in hw/scsi/scsi-disk.c because scsi_disk_emulate_mode_select does not
prevent s->qdev.blocksize from being 256. This stops QEMU and the guest
immediately.

References:
https://nvd.nist.gov/vuln/detail/CVE-2023-42467
https://gitlab.com/qemu-project/qemu/-/issues/1813

(From OE-Core rev: 4925ac7120605d551e1b28196b4a4dab7bc72b66)

Signed-off-by: Yogita Urade <yogita.urade@windriver.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>
This commit is contained in:
Yogita Urade
2023-10-04 11:19:31 +00:00
committed by Steve Sakoman
parent ae2c4f104b
commit 30969f3e97
2 changed files with 50 additions and 0 deletions

View File

@@ -42,6 +42,7 @@ SRC_URI = "https://download.qemu.org/${BPN}-${PV}.tar.xz \
file://CVE-2023-2861.patch \
file://CVE-2023-3354.patch \
file://CVE-2023-3180.patch \
file://CVE-2023-42467.patch \
"
UPSTREAM_CHECK_REGEX = "qemu-(?P<pver>\d+(\.\d+)+)\.tar"

View File

@@ -0,0 +1,49 @@
From 7cfcc79b0ab800959716738aff9419f53fc68c9c Mon Sep 17 00:00:00 2001
From: Thomas Huth <thuth@redhat.com>
Date: Wed, 4 Oct 2023 08:54:13 +0000
Subject: [PATCH] hw/scsi/scsi-disk: Disallow block sizes smaller than 512
[CVE-2023-42467]
We are doing things like
nb_sectors /= (s->qdev.blocksize / BDRV_SECTOR_SIZE);
in the code here (e.g. in scsi_disk_emulate_mode_sense()), so if
the blocksize is smaller than BDRV_SECTOR_SIZE (=512), this crashes
with a division by 0 exception. Thus disallow block sizes of 256
bytes to avoid this situation.
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1813
CVE: 2023-42467
Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-ID: <20230925091854.49198-1-thuth@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
CVE: CVE-2023-42467
Upstream-Status: Backport [https://gitlab.com/qemu-project/qemu/-/commit/7cfcc79b0ab800959716738aff9419f53fc68c9c]
Signed-off-by: Yogita Urade <yogita.urade@windriver.com>
---
hw/scsi/scsi-disk.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
index e493c2881..915e0369c 100644
--- a/hw/scsi/scsi-disk.c
+++ b/hw/scsi/scsi-disk.c
@@ -1624,9 +1624,10 @@ static void scsi_disk_emulate_mode_select(SCSIDiskReq *r, uint8_t *inbuf)
* Since the existing code only checks/updates bits 8-15 of the block
* size, restrict ourselves to the same requirement for now to ensure
* that a block size set by a block descriptor and then read back by
- * a subsequent SCSI command will be the same
+ * a subsequent SCSI command will be the same. Also disallow a block
+ * size of 256 since we cannot handle anything below BDRV_SECTOR_SIZE.
*/
- if (bs && !(bs & ~0xff00) && bs != s->qdev.blocksize) {
+ if (bs && !(bs & ~0xfe00) && bs != s->qdev.blocksize) {
s->qdev.blocksize = bs;
trace_scsi_disk_mode_select_set_blocksize(s->qdev.blocksize);
}
--
2.40.0