From 2318681bf850996a3e9c682ca3290aa9f05fd15c Mon Sep 17 00:00:00 2001

From: Kevin Wolf <kwolf@redhat.com>

Date: Tue, 25 Mar 2014 14:23:31 +0100

Subject: [PATCH 24/49] qcow2: Validate snapshot table offset/size (CVE-2014-0144)

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

Message-id: <1395753835-7591-25-git-send-email-kwolf@redhat.com>

Patchwork-id: n/a

O-Subject: [virt-devel] [EMBARGOED RHEL-7.0 qemu-kvm PATCH 24/48] qcow2: Validate snapshot table offset/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

This avoid unbounded memory allocation and fixes a potential buffer

overflow on 32 bit hosts.

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

---

 block/qcow2-snapshot.c     |   29 ++++-------------------------

 block/qcow2.c              |   15 +++++++++++++++

 block/qcow2.h              |   29 ++++++++++++++++++++++++++++-

 tests/qemu-iotests/080     |   27 +++++++++++++++++++++++++++

 tests/qemu-iotests/080.out |   17 +++++++++++++++++

 5 files changed, 91 insertions(+), 26 deletions(-)

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

index aa88c51..5d73506 100644

--- a/block/qcow2-snapshot.c

+++ b/block/qcow2-snapshot.c

@@ -26,31 +26,6 @@

 #include "block/block_int.h"

 #include "block/qcow2.h"

-typedef struct QEMU_PACKED QCowSnapshotHeader {

-    /* header is 8 byte aligned */

-    uint64_t l1_table_offset;

-

-    uint32_t l1_size;

-    uint16_t id_str_size;

-    uint16_t name_size;

-

-    uint32_t date_sec;

-    uint32_t date_nsec;

-

-    uint64_t vm_clock_nsec;

-

-    uint32_t vm_state_size;

-    uint32_t extra_data_size; /* for extension */

-    /* extra data follows */

-    /* id_str follows */

-    /* name follows  */

-} QCowSnapshotHeader;

-

-typedef struct QEMU_PACKED QCowSnapshotExtraData {

-    uint64_t vm_state_size_large;

-    uint64_t disk_size;

-} QCowSnapshotExtraData;

-

 void qcow2_free_snapshots(BlockDriverState *bs)

 {

     BDRVQcowState *s = bs->opaque;

@@ -334,6 +309,10 @@ int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info)

     uint64_t *l1_table = NULL;

     int64_t l1_table_offset;

+    if (s->nb_snapshots >= QCOW_MAX_SNAPSHOTS) {

+        return -EFBIG;

+    }

+

     memset(sn, 0, sizeof(*sn));

     /* Generate an ID if it wasn't passed */

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

index 5513fac..8c74dea 100644

--- a/block/qcow2.c

+++ b/block/qcow2.c

@@ -622,6 +622,21 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,

         goto fail;

     }

+    /* Snapshot table offset/length */

+    if (header.nb_snapshots > QCOW_MAX_SNAPSHOTS) {

+        error_setg(errp, "Too many snapshots");

+        ret = -EINVAL;

+        goto fail;

+    }

+

+    ret = validate_table_offset(bs, header.snapshots_offset,

+                                header.nb_snapshots,

+                                sizeof(QCowSnapshotHeader));

+    if (ret < 0) {

+        error_setg(errp, "Invalid snapshot table offset");

+        goto fail;

+    }

+

     s->snapshots_offset = header.snapshots_offset;

     s->nb_snapshots = header.nb_snapshots;

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

index 4a653c5..5efc96e 100644

--- a/block/qcow2.h

+++ b/block/qcow2.h

@@ -38,6 +38,7 @@

 #define QCOW_CRYPT_AES  1

 #define QCOW_MAX_CRYPT_CLUSTERS 32

+#define QCOW_MAX_SNAPSHOTS 65536

 /* indicate that the refcount of the referenced cluster is exactly one. */

 #define QCOW_OFLAG_COPIED     (1LL << 63)

@@ -97,6 +98,32 @@ typedef struct QCowHeader {

     uint32_t header_length;

 } QCowHeader;

+typedef struct QEMU_PACKED QCowSnapshotHeader {

+    /* header is 8 byte aligned */

+    uint64_t l1_table_offset;

+

+    uint32_t l1_size;

+    uint16_t id_str_size;

+    uint16_t name_size;

+

+    uint32_t date_sec;

+    uint32_t date_nsec;

+

+    uint64_t vm_clock_nsec;

+

+    uint32_t vm_state_size;

+    uint32_t extra_data_size; /* for extension */

+    /* extra data follows */

+    /* id_str follows */

+    /* name follows  */

+} QCowSnapshotHeader;

+

+typedef struct QEMU_PACKED QCowSnapshotExtraData {

+    uint64_t vm_state_size_large;

+    uint64_t disk_size;

+} QCowSnapshotExtraData;

+

+

 typedef struct QCowSnapshot {

     uint64_t l1_table_offset;

     uint32_t l1_size;

@@ -202,7 +229,7 @@ typedef struct BDRVQcowState {

     AES_KEY aes_decrypt_key;

     uint64_t snapshots_offset;

     int snapshots_size;

-    int nb_snapshots;

+    unsigned int nb_snapshots;

     QCowSnapshot *snapshots;

     int flags;

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

index f58ac73..8a8b460 100755

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

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

@@ -47,6 +47,8 @@ header_size=104

 offset_backing_file_offset=8

 offset_refcount_table_offset=48

 offset_refcount_table_clusters=56

+offset_nb_snapshots=60

+offset_snapshots_offset=64

 offset_header_size=100

 offset_ext_magic=$header_size

 offset_ext_size=$((header_size + 4))

@@ -90,6 +92,31 @@ poke_file "$TEST_IMG" "$offset_refcount_table_offset" "\xff\xff\xff\xff\xff\xff\

 poke_file "$TEST_IMG" "$offset_refcount_table_clusters" "\x00\x00\x00\x7f"

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

+echo

+echo "== Invalid snapshot table =="

+_make_test_img 64M

+poke_file "$TEST_IMG" "$offset_nb_snapshots" "\xff\xff\xff\xff"

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

+poke_file "$TEST_IMG" "$offset_nb_snapshots" "\x7f\xff\xff\xff"

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

+

+poke_file "$TEST_IMG" "$offset_snapshots_offset" "\xff\xff\xff\xff\xff\xff\x00\x00"

+poke_file "$TEST_IMG" "$offset_nb_snapshots" "\x00\x00\xff\xff"

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

+

+poke_file "$TEST_IMG" "$offset_snapshots_offset" "\x12\x34\x56\x78\x90\xab\xcd\xef"

+poke_file "$TEST_IMG" "$offset_nb_snapshots" "\x00\x00\x00\x00"

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

+

+echo

+echo "== Hitting snapshot table size limit =="

+_make_test_img 64M

+# Put the refcount table in a more or less safe place (16 MB)

+poke_file "$TEST_IMG" "$offset_snapshots_offset" "\x00\x00\x00\x00\x01\x00\x00\x00"

+poke_file "$TEST_IMG" "$offset_nb_snapshots" "\x00\x01\x00\x00"

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

+{ $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 f919b58..b06f47f 100644

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

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

@@ -30,4 +30,21 @@ no file open, try 'help open'

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

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

 no file open, try 'help open'

+

+== Invalid snapshot table ==

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

+qemu-io: can't open device TEST_DIR/t.qcow2: Too many snapshots

+no file open, try 'help open'

+qemu-io: can't open device TEST_DIR/t.qcow2: Too many snapshots

+no file open, try 'help open'

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

+no file open, try 'help open'

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

+no file open, try 'help open'

+

+== Hitting snapshot table size limit ==

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

+qemu-img: Could not create snapshot 'test': -27 (File too large)

+read 512/512 bytes at offset 0

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

 *** done

-- 

1.7.1