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vhost: make sure log_num < in_num (CVE-2019-14835)

This commit is contained in:
Salvatore Bonaccorso 2019-09-13 06:11:19 +02:00
parent 782d6ea880
commit 78f0b2574a
3 changed files with 58 additions and 0 deletions
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3
debian/changelog vendored
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@ -5,6 +5,9 @@ linux (4.19.67-2+deb10u1) UNRELEASED; urgency=medium
* ALSA: usb-audio: Fix a stack buffer overflow bug in check_input_term
(CVE-2019-15118)
[ Salvatore Bonaccorso ]
* vhost: make sure log_num < in_num (CVE-2019-14835)
-- Romain Perier <romain.perier@gmail.com> Wed, 28 Aug 2019 13:28:09 +0200
linux (4.19.67-2) buster; urgency=medium

54
debian/patches/bugfix/all/vhost-make-sure-log_num-in_num.patch vendored Normal file
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@ -0,0 +1,54 @@
From: yongduan <yongduan@tencent.com>
Date: Wed, 11 Sep 2019 17:44:24 +0800
Subject: vhost: make sure log_num < in_num
Origin: https://git.kernel.org/linus/060423bfdee3f8bc6e2c1bac97de24d5415e2bc4
Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2019-14835
The code assumes log_num < in_num everywhere, and that is true as long as
in_num is incremented by descriptor iov count, and log_num by 1. However
this breaks if there's a zero sized descriptor.
As a result, if a malicious guest creates a vring desc with desc.len = 0,
it may cause the host kernel to crash by overflowing the log array. This
bug can be triggered during the VM migration.
There's no need to log when desc.len = 0, so just don't increment log_num
in this case.
Fixes: 3a4d5c94e959 ("vhost_net: a kernel-level virtio server")
Cc: stable@vger.kernel.org
Reviewed-by: Lidong Chen <lidongchen@tencent.com>
Signed-off-by: ruippan <ruippan@tencent.com>
Signed-off-by: yongduan <yongduan@tencent.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
drivers/vhost/vhost.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 34ea219936e3..acabf20b069e 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -2180,7 +2180,7 @@ static int get_indirect(struct vhost_virtqueue *vq,
/* If this is an input descriptor, increment that count. */
if (access == VHOST_ACCESS_WO) {
*in_num += ret;
- if (unlikely(log)) {
+ if (unlikely(log && ret)) {
log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
log[*log_num].len = vhost32_to_cpu(vq, desc.len);
++*log_num;
@@ -2321,7 +2321,7 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq,
/* If this is an input descriptor,
* increment that count. */
*in_num += ret;
- if (unlikely(log)) {
+ if (unlikely(log && ret)) {
log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
log[*log_num].len = vhost32_to_cpu(vq, desc.len);
++*log_num;
--
2.23.0

1
debian/patches/series vendored
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@ -164,6 +164,7 @@ debian/ntfs-mark-it-as-broken.patch
bugfix/all/netfilter-conntrack-use-consistent-ct-id-hash-calcul.patch
bugfix/all/ALSA-usb-audio-Fix-an-OOB-bug-in-parse_audio_mixer_unit.patch
bugfix/all/ALSA-usb-audio-Fix-a-stack-buffer-overflow-bug-in-check_input_term.patch
bugfix/all/vhost-make-sure-log_num-in_num.patch
# Fix exported symbol versions
bugfix/all/module-disable-matching-missing-version-crc.patch