From 1235b1580890e2a034bb24f89a89311d296d2622 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Tue, 25 Mar 2014 14:23:51 +0100 Subject: [PATCH 44/49] qcow2: Fix L1 allocation size in qcow2_snapshot_load_tmp() (CVE-2014-0145) RH-Author: Kevin Wolf Message-id: <1395753835-7591-45-git-send-email-kwolf@redhat.com> Patchwork-id: n/a O-Subject: [virt-devel] [EMBARGOED RHEL-7.0 qemu-kvm PATCH 44/48] qcow2: Fix L1 allocation size in qcow2_snapshot_load_tmp() (CVE-2014-0145) Bugzilla: 1079325 RH-Acked-by: Jeff Cody RH-Acked-by: Stefan Hajnoczi RH-Acked-by: Paolo Bonzini Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1079325 Upstream status: Embargoed For the L1 table to loaded for an internal snapshot, the code allocated only enough memory to hold the currently active L1 table. If the snapshot's L1 table is actually larger than the current one, this leads to a buffer overflow. Signed-off-by: Kevin Wolf --- block/qcow2-snapshot.c | 2 +- tests/qemu-iotests/029 | 18 +++++++++++++++++- tests/qemu-iotests/029.out | 4 ++++ 3 files changed, 22 insertions(+), 2 deletions(-) diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c index 5d73506..b29f7bd 100644 --- a/block/qcow2-snapshot.c +++ b/block/qcow2-snapshot.c @@ -635,7 +635,7 @@ int qcow2_snapshot_load_tmp(BlockDriverState *bs, const char *snapshot_name) sn = &s->snapshots[snapshot_index]; /* Allocate and read in the snapshot's L1 table */ - new_l1_bytes = s->l1_size * sizeof(uint64_t); + new_l1_bytes = sn->l1_size * sizeof(uint64_t); new_l1_table = g_malloc0(align_offset(new_l1_bytes, 512)); ret = bdrv_pread(bs->file, sn->l1_table_offset, new_l1_table, new_l1_bytes); diff --git a/tests/qemu-iotests/029 b/tests/qemu-iotests/029 index 567e071..fa46ace 100755 --- a/tests/qemu-iotests/029 +++ b/tests/qemu-iotests/029 @@ -30,7 +30,8 @@ status=1 # failure is the default! _cleanup() { - _cleanup_test_img + rm -f $TEST_IMG.snap + _cleanup_test_img } trap "_cleanup; exit \$status" 0 1 2 3 15 @@ -44,6 +45,9 @@ _supported_fmt qcow2 _supported_proto generic _supported_os Linux +offset_size=24 +offset_l1_size=36 + echo echo Test loading internal snapshots where the L1 table of the snapshot echo is smaller than the current L1 table. @@ -77,6 +81,18 @@ _make_test_img 64M _check_test_img +echo +echo "qcow2_snapshot_load_tmp() should take the L1 size from the snapshot" +echo + +CLUSTER_SIZE=512 +_make_test_img 64M +{ $QEMU_IMG snapshot -c foo $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir +poke_file "$TEST_IMG" "$offset_size" "\x00\x00\x00\x00\x00\x00\x02\x00" +poke_file "$TEST_IMG" "$offset_l1_size" "\x00\x00\x00\x01" +{ $QEMU_IMG convert -s foo $TEST_IMG $TEST_IMG.snap; } 2>&1 | _filter_qemu_io | _filter_testdir + + # success, all done echo "*** done" rm -f $seq.full diff --git a/tests/qemu-iotests/029.out b/tests/qemu-iotests/029.out index 9029698..ce0e64d 100644 --- a/tests/qemu-iotests/029.out +++ b/tests/qemu-iotests/029.out @@ -20,4 +20,8 @@ wrote 4096/4096 bytes at offset 1099511627776 read 4096/4096 bytes at offset 1099511627776 4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) No errors were found on the image. + +qcow2_snapshot_load_tmp() should take the L1 size from the snapshot + +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 *** done -- 1.7.1