| From 0f9e33b29b76a647c903753a0758b9c85e75d73a Mon Sep 17 00:00:00 2001 |
| From: Kevin Wolf <kwolf@redhat.com> |
| Date: Tue, 25 Mar 2014 14:23:29 +0100 |
| Subject: [PATCH 22/49] qcow2: Check refcount table size (CVE-2014-0144) |
| |
| RH-Author: Kevin Wolf <kwolf@redhat.com> |
| Message-id: <1395753835-7591-23-git-send-email-kwolf@redhat.com> |
| Patchwork-id: n/a |
| O-Subject: [virt-devel] [EMBARGOED RHEL-7.0 qemu-kvm PATCH 22/48] qcow2: Check refcount table size (CVE-2014-0144) |
| Bugzilla: 1079455 |
| 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=1079455 |
| Upstream status: Embargoed |
| |
| Limit the in-memory reference count table size to 8 MB, it's enough in |
| practice. This fixes an unbounded allocation as well as a buffer |
| overflow in qcow2_refcount_init(). |
| |
| Signed-off-by: Kevin Wolf <kwolf@redhat.com> |
| |
| block/qcow2-refcount.c | 4 +++- |
| block/qcow2.c | 9 +++++++++ |
| tests/qemu-iotests/080 | 10 ++++++++++ |
| tests/qemu-iotests/080.out | 7 +++++++ |
| 4 files changed, 29 insertions(+), 1 deletions(-) |
| |
| diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c |
| index 09c638f..13ea5f7 100644 |
| |
| |
| @@ -40,8 +40,10 @@ static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs, |
| int qcow2_refcount_init(BlockDriverState *bs) |
| { |
| BDRVQcowState *s = bs->opaque; |
| - int ret, refcount_table_size2, i; |
| + unsigned int refcount_table_size2, i; |
| + int ret; |
| |
| + assert(s->refcount_table_size <= INT_MAX / sizeof(uint64_t)); |
| refcount_table_size2 = s->refcount_table_size * sizeof(uint64_t); |
| s->refcount_table = g_malloc(refcount_table_size2); |
| if (s->refcount_table_size > 0) { |
| diff --git a/block/qcow2.c b/block/qcow2.c |
| index 5568cf9..a7780ac 100644 |
| |
| |
| @@ -576,10 +576,19 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags, |
| s->csize_shift = (62 - (s->cluster_bits - 8)); |
| s->csize_mask = (1 << (s->cluster_bits - 8)) - 1; |
| s->cluster_offset_mask = (1LL << s->csize_shift) - 1; |
| + |
| s->refcount_table_offset = header.refcount_table_offset; |
| s->refcount_table_size = |
| header.refcount_table_clusters << (s->cluster_bits - 3); |
| |
| + if (header.refcount_table_clusters > (0x800000 >> s->cluster_bits)) { |
| + /* 8 MB refcount table is enough for 2 PB images at 64k cluster size |
| + * (128 GB for 512 byte clusters, 2 EB for 2 MB clusters) */ |
| + error_setg(errp, "Reference count table too large"); |
| + ret = -EINVAL; |
| + goto fail; |
| + } |
| + |
| s->snapshots_offset = header.snapshots_offset; |
| s->nb_snapshots = header.nb_snapshots; |
| |
| diff --git a/tests/qemu-iotests/080 b/tests/qemu-iotests/080 |
| index 6d588dd..6179e05 100755 |
| |
| |
| @@ -45,6 +45,7 @@ _supported_os Linux |
| header_size=104 |
| |
| offset_backing_file_offset=8 |
| +offset_refcount_table_clusters=56 |
| offset_header_size=100 |
| offset_ext_magic=$header_size |
| offset_ext_size=$((header_size + 4)) |
| @@ -67,6 +68,15 @@ poke_file "$TEST_IMG" "$offset_ext_size" "\x7f\xff\xff\xff" |
| poke_file "$TEST_IMG" "$offset_backing_file_offset" "\x00\x00\x00\x00\x00\x00\x00\x00" |
| { $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir |
| |
| +echo |
| +echo "== Huge refcount table size ==" |
| +_make_test_img 64M |
| +poke_file "$TEST_IMG" "$offset_refcount_table_clusters" "\xff\xff\xff\xff" |
| +{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir |
| +poke_file "$TEST_IMG" "$offset_refcount_table_clusters" "\x00\x02\x00\x01" |
| +{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir |
| + |
| + |
| # success, all done |
| echo "*** done" |
| rm -f $seq.full |
| diff --git a/tests/qemu-iotests/080.out b/tests/qemu-iotests/080.out |
| index 48c40aa..6fef6d9 100644 |
| |
| |
| @@ -13,4 +13,11 @@ qemu-io: can't open device TEST_DIR/t.qcow2: Invalid backing file offset |
| no file open, try 'help open' |
| qemu-io: can't open device TEST_DIR/t.qcow2: Header extension too large |
| no file open, try 'help open' |
| + |
| +== Huge refcount table size == |
| +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 |
| +qemu-io: can't open device TEST_DIR/t.qcow2: Reference count table too large |
| +no file open, try 'help open' |
| +qemu-io: can't open device TEST_DIR/t.qcow2: Reference count table too large |
| +no file open, try 'help open' |
| *** done |
| -- |
| 1.7.1 |
| |