From 4ce3cdbea5f0006ec857767f2dc74a02fffd0cb5 Mon Sep 17 00:00:00 2001

From: Kevin Wolf <kwolf@redhat.com>

Date: Tue, 25 Mar 2014 14:23:50 +0100

Subject: [PATCH 43/49] qcow2: Fix NULL dereference in qcow2_open() error path (CVE-2014-0146)

RH-Author: Kevin Wolf <kwolf@redhat.com>

Message-id: <1395753835-7591-44-git-send-email-kwolf@redhat.com>

Patchwork-id: n/a

O-Subject: [virt-devel] [EMBARGOED RHEL-7.0 qemu-kvm PATCH 43/48] qcow2: Fix NULL dereference in qcow2_open() error path (CVE-2014-0146)

Bugzilla: 1079333

RH-Acked-by: Jeff Cody <jcody@redhat.com>

RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1079333

Upstream status: Embargoed

The qcow2 code assumes that s->snapshots is non-NULL if s->nb_snapshots

!= 0. By having the initialisation of both fields separated in

qcow2_open(), any error occuring in between would cause the error path

to dereference NULL in qcow2_free_snapshots() if the image had any

snapshots.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>

---

 block/qcow2.c              |    7 ++++---

 tests/qemu-iotests/080     |    7 +++++++

 tests/qemu-iotests/080.out |    4 ++++

 3 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/block/qcow2.c b/block/qcow2.c

index db9f667..33b46b8 100644

--- a/block/qcow2.c

+++ b/block/qcow2.c

@@ -636,9 +636,6 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,

         goto fail;

     }

-    s->snapshots_offset = header.snapshots_offset;

-    s->nb_snapshots = header.nb_snapshots;

-

     /* read the level 1 table */

     if (header.l1_size > 0x2000000) {

         /* 32 MB L1 table is enough for 2 PB images at 64k cluster size

@@ -733,6 +730,10 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,

         bs->backing_file[len] = '\0';

     }

+    /* Internal snapshots */

+    s->snapshots_offset = header.snapshots_offset;

+    s->nb_snapshots = header.nb_snapshots;

+

     ret = qcow2_read_snapshots(bs);

     if (ret < 0) {

         error_setg_errno(errp, -ret, "Could not read snapshots");

diff --git a/tests/qemu-iotests/080 b/tests/qemu-iotests/080

index 56f8903..59e7a44 100755

--- a/tests/qemu-iotests/080

+++ b/tests/qemu-iotests/080

@@ -139,6 +139,13 @@ poke_file "$TEST_IMG" "$offset_l1_size" "\x00\x00\x00\x01"

 { $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir

 echo

+echo "== Invalid L1 table (with internal snapshot in the image) =="

+_make_test_img 64M

+{ $QEMU_IMG snapshot -c foo $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir

+poke_file "$TEST_IMG" "$offset_l1_size" "\x00\x00\x00\x00"

+_img_info

+

+echo

 echo "== Invalid backing file size =="

 _make_test_img 64M

 poke_file "$TEST_IMG" "$offset_backing_file_offset" "\x00\x00\x00\x00\x00\x00\x10\x00"

diff --git a/tests/qemu-iotests/080.out b/tests/qemu-iotests/080.out

index 303d6c3..4d84fbf 100644

--- a/tests/qemu-iotests/080.out

+++ b/tests/qemu-iotests/080.out

@@ -59,6 +59,10 @@ no file open, try 'help open'

 qemu-io: can't open device TEST_DIR/t.qcow2: Invalid L1 table offset

 no file open, try 'help open'

+== Invalid L1 table (with internal snapshot in the image) ==

+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 

+qemu-img: Could not open 'TEST_DIR/t.IMGFMT': L1 table is too small

+

 == Invalid backing file size ==

 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 

 qemu-io: can't open device TEST_DIR/t.qcow2: Backing file name too long

-- 

1.7.1