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From 4ce3cdbea5f0006ec857767f2dc74a02fffd0cb5 Mon Sep 17 00:00:00 2001
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From: Kevin Wolf <kwolf@redhat.com>
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Date: Tue, 25 Mar 2014 14:23:50 +0100
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Subject: [PATCH 43/49] qcow2: Fix NULL dereference in qcow2_open() error path (CVE-2014-0146)
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RH-Author: Kevin Wolf <kwolf@redhat.com>
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Message-id: <1395753835-7591-44-git-send-email-kwolf@redhat.com>
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Patchwork-id: n/a
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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)
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Bugzilla: 1079333
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RH-Acked-by: Jeff Cody <jcody@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1079333
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Upstream status: Embargoed
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The qcow2 code assumes that s->snapshots is non-NULL if s->nb_snapshots
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!= 0. By having the initialisation of both fields separated in
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qcow2_open(), any error occuring in between would cause the error path
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to dereference NULL in qcow2_free_snapshots() if the image had any
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snapshots.
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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---
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 block/qcow2.c              |    7 ++++---
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 tests/qemu-iotests/080     |    7 +++++++
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 tests/qemu-iotests/080.out |    4 ++++
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 3 files changed, 15 insertions(+), 3 deletions(-)
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diff --git a/block/qcow2.c b/block/qcow2.c
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index db9f667..33b46b8 100644
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--- a/block/qcow2.c
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+++ b/block/qcow2.c
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@@ -636,9 +636,6 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
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         goto fail;
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     }
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-    s->snapshots_offset = header.snapshots_offset;
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-    s->nb_snapshots = header.nb_snapshots;
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-
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     /* read the level 1 table */
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     if (header.l1_size > 0x2000000) {
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         /* 32 MB L1 table is enough for 2 PB images at 64k cluster size
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@@ -733,6 +730,10 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
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         bs->backing_file[len] = '\0';
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     }
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+    /* Internal snapshots */
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+    s->snapshots_offset = header.snapshots_offset;
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+    s->nb_snapshots = header.nb_snapshots;
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+
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     ret = qcow2_read_snapshots(bs);
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     if (ret < 0) {
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         error_setg_errno(errp, -ret, "Could not read snapshots");
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diff --git a/tests/qemu-iotests/080 b/tests/qemu-iotests/080
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index 56f8903..59e7a44 100755
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--- a/tests/qemu-iotests/080
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+++ b/tests/qemu-iotests/080
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@@ -139,6 +139,13 @@ poke_file "$TEST_IMG" "$offset_l1_size" "\x00\x00\x00\x01"
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 { $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
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 echo
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+echo "== Invalid L1 table (with internal snapshot in the image) =="
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+_make_test_img 64M
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+{ $QEMU_IMG snapshot -c foo $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
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+poke_file "$TEST_IMG" "$offset_l1_size" "\x00\x00\x00\x00"
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+_img_info
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+
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+echo
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 echo "== Invalid backing file size =="
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 _make_test_img 64M
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 poke_file "$TEST_IMG" "$offset_backing_file_offset" "\x00\x00\x00\x00\x00\x00\x10\x00"
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diff --git a/tests/qemu-iotests/080.out b/tests/qemu-iotests/080.out
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index 303d6c3..4d84fbf 100644
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--- a/tests/qemu-iotests/080.out
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+++ b/tests/qemu-iotests/080.out
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@@ -59,6 +59,10 @@ no file open, try 'help open'
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 qemu-io: can't open device TEST_DIR/t.qcow2: Invalid L1 table offset
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 no file open, try 'help open'
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+== Invalid L1 table (with internal snapshot in the image) ==
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+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 
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+qemu-img: Could not open 'TEST_DIR/t.IMGFMT': L1 table is too small
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+
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 == Invalid backing file size ==
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 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 
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 qemu-io: can't open device TEST_DIR/t.qcow2: Backing file name too long
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-- 
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1.7.1
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