From ba8c0cc73f3a13b5621c8fe44eb8af20ddb9c5d0 Mon Sep 17 00:00:00 2001

From: Stefan Hajnoczi <stefanha@redhat.com>

Date: Tue, 25 Mar 2014 14:23:11 +0100

Subject: [PATCH 04/49] block/cloop: validate block_size header field (CVE-2014-0144)

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

Message-id: <1395753835-7591-5-git-send-email-kwolf@redhat.com>

Patchwork-id: n/a

O-Subject: [virt-devel] [EMBARGOED RHEL-7.0 qemu-kvm PATCH 04/48] block/cloop: validate block_size header field (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>

From: Stefan Hajnoczi <stefanha@redhat.com>

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1079455

Upstream status: Embargoed

Avoid unbounded s->uncompressed_block memory allocation by checking that

the block_size header field has a reasonable value. Also enforce the

assumption that the value is a non-zero multiple of 512.

These constraints conform to cloop 2.639's code so we accept existing

image files.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

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

---

 block/cloop.c              |   23 +++++++++++++++++++++++

 tests/qemu-iotests/075     |   20 ++++++++++++++++++++

 tests/qemu-iotests/075.out |   12 ++++++++++++

 3 files changed, 55 insertions(+), 0 deletions(-)

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

index b907023..f021663 100644

--- a/block/cloop.c

+++ b/block/cloop.c

@@ -26,6 +26,9 @@

 #include "qemu/module.h"

 #include <zlib.h>

+/* Maximum compressed block size */

+#define MAX_BLOCK_SIZE (64 * 1024 * 1024)

+

 typedef struct BDRVCloopState {

     CoMutex lock;

     uint32_t block_size;

@@ -68,6 +71,26 @@ static int cloop_open(BlockDriverState *bs, QDict *options, int flags,

         return ret;

     }

     s->block_size = be32_to_cpu(s->block_size);

+    if (s->block_size % 512) {

+        error_setg(errp, "block_size %u must be a multiple of 512",

+                   s->block_size);

+        return -EINVAL;

+    }

+    if (s->block_size == 0) {

+        error_setg(errp, "block_size cannot be zero");

+        return -EINVAL;

+    }

+

+    /* cloop's create_compressed_fs.c warns about block sizes beyond 256 KB but

+     * we can accept more.  Prevent ridiculous values like 4 GB - 1 since we

+     * need a buffer this big.

+     */

+    if (s->block_size > MAX_BLOCK_SIZE) {

+        error_setg(errp, "block_size %u must be %u MB or less",

+                   s->block_size,

+                   MAX_BLOCK_SIZE / (1024 * 1024));

+        return -EINVAL;

+    }

     ret = bdrv_pread(bs->file, 128 + 4, &s->n_blocks, 4);

     if (ret < 0) {

diff --git a/tests/qemu-iotests/075 b/tests/qemu-iotests/075

index 88ae8bb..8f54a99 100755

--- a/tests/qemu-iotests/075

+++ b/tests/qemu-iotests/075

@@ -42,11 +42,31 @@ _supported_fmt cloop

 _supported_proto generic

 _supported_os Linux

+block_size_offset=128

+

 echo

 echo "== check that the first sector can be read =="

 _use_sample_img simple-pattern.cloop.bz2

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

+echo

+echo "== block_size must be a multiple of 512 =="

+_use_sample_img simple-pattern.cloop.bz2

+poke_file "$TEST_IMG" "$block_size_offset" "\x00\x00\x02\x01"

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

+

+echo

+echo "== block_size cannot be zero =="

+_use_sample_img simple-pattern.cloop.bz2

+poke_file "$TEST_IMG" "$block_size_offset" "\x00\x00\x00\x00"

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

+

+echo

+echo "== huge block_size ==="

+_use_sample_img simple-pattern.cloop.bz2

+poke_file "$TEST_IMG" "$block_size_offset" "\xff\xff\xfe\x00"

+$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/075.out b/tests/qemu-iotests/075.out

index 26661fa..d362c95 100644

--- a/tests/qemu-iotests/075.out

+++ b/tests/qemu-iotests/075.out

@@ -3,4 +3,16 @@ QA output created by 075

 == check that the first sector can be read ==

 read 512/512 bytes at offset 0

 512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

+

+== block_size must be a multiple of 512 ==

+qemu-io: can't open device TEST_DIR/simple-pattern.cloop: block_size 513 must be a multiple of 512

+no file open, try 'help open'

+

+== block_size cannot be zero ==

+qemu-io: can't open device TEST_DIR/simple-pattern.cloop: block_size cannot be zero

+no file open, try 'help open'

+

+== huge block_size ===

+qemu-io: can't open device TEST_DIR/simple-pattern.cloop: block_size 4294966784 must be 64 MB or less

+no file open, try 'help open'

 *** done

-- 

1.7.1