From cac9ac8f0173f95893fbc62fa67fcf04e4c76f5f Mon Sep 17 00:00:00 2001

From: Stefan Hajnoczi <stefanha@redhat.com>

Date: Tue, 25 Mar 2014 14:23:15 +0100

Subject: [PATCH 08/49] size off-by-one

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

Message-id: <1395753835-7591-9-git-send-email-kwolf@redhat.com>

Patchwork-id: n/a

O-Subject: [virt-devel] [EMBARGOED RHEL-7.0 qemu-kvm PATCH 08/48] block/cloop: fix offsets[] size off-by-one

Bugzilla: 1066691

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=1066691

Upstream status: Series embargoed

cloop stores the number of compressed blocks in the n_blocks header

field. The file actually contains n_blocks + 1 offsets, where the extra

offset is the end-of-file offset.

The following line in cloop_read_block() results in an out-of-bounds

offsets[] access:

uint32_t bytes = s->offsets[block_num + 1] - s->offsets[block_num];

This patch allocates and loads the extra offset so that

cloop_read_block() works correctly when the last block is accessed.

Notice that we must free s->offsets[] unconditionally now since there is

always an end-of-file offset.

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

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

---

 block/cloop.c              |   12 +++++-------

 tests/qemu-iotests/075     |    5 +++++

 tests/qemu-iotests/075.out |    4 ++++

 3 files changed, 14 insertions(+), 7 deletions(-)

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

index 55a804f..b6ad50f 100644

--- a/block/cloop.c

+++ b/block/cloop.c

@@ -99,14 +99,14 @@ static int cloop_open(BlockDriverState *bs, QDict *options, int flags,

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

     /* read offsets */

-    if (s->n_blocks > UINT32_MAX / sizeof(uint64_t)) {

+    if (s->n_blocks > (UINT32_MAX - 1) / sizeof(uint64_t)) {

         /* Prevent integer overflow */

         error_setg(errp, "n_blocks %u must be %zu or less",

                    s->n_blocks,

-                   UINT32_MAX / sizeof(uint64_t));

+                   (UINT32_MAX - 1) / sizeof(uint64_t));

         return -EINVAL;

     }

-    offsets_size = s->n_blocks * sizeof(uint64_t);

+    offsets_size = (s->n_blocks + 1) * sizeof(uint64_t);

     if (offsets_size > 512 * 1024 * 1024) {

         /* Prevent ridiculous offsets_size which causes memory allocation to

          * fail or overflows bdrv_pread() size.  In practice the 512 MB

@@ -123,7 +123,7 @@ static int cloop_open(BlockDriverState *bs, QDict *options, int flags,

         goto fail;

     }

-    for(i=0;i<s->n_blocks;i++) {

+    for (i = 0; i < s->n_blocks + 1; i++) {

         uint64_t size;

         s->offsets[i] = be64_to_cpu(s->offsets[i]);

@@ -243,9 +243,7 @@ static coroutine_fn int cloop_co_read(BlockDriverState *bs, int64_t sector_num,

 static void cloop_close(BlockDriverState *bs)

 {

     BDRVCloopState *s = bs->opaque;

-    if (s->n_blocks > 0) {

-        g_free(s->offsets);

-    }

+    g_free(s->offsets);

     g_free(s->compressed_block);

     g_free(s->uncompressed_block);

     inflateEnd(&s->zstream);

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

index d74fb33..40032c5 100755

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

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

@@ -52,6 +52,11 @@ _use_sample_img simple-pattern.cloop.bz2

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

 echo

+echo "== check that the last sector can be read =="

+_use_sample_img simple-pattern.cloop.bz2

+$QEMU_IO -c "read $((1024 * 1024 - 512)) 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"

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

index 911cd3b..5f1d6c1 100644

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

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

@@ -4,6 +4,10 @@ QA output created by 075

 read 512/512 bytes at offset 0

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

+== check that the last sector can be read ==

+read 512/512 bytes at offset 1048064

+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'

-- 

1.7.1