diff options
| author | Stefan Hajnoczi <stefanha@redhat.com> | 2014-03-26 13:05:26 +0100 |
|---|---|---|
| committer | Stefan Hajnoczi <stefanha@redhat.com> | 2014-04-01 13:59:47 +0200 |
| commit | 509a41bab5306181044b5fff02eadf96d9c8676a (patch) | |
| tree | d539979df142d4d46cfc0137032d0098fc973dc8 | |
| parent | d65f97a82c4ed48374a764c769d4ba1ea9724e97 (diff) | |
block/cloop: prevent offsets_size integer overflow (CVE-2014-0143)
The following integer overflow in offsets_size can lead to out-of-bounds
memory stores when n_blocks has a huge value:
uint32_t n_blocks, offsets_size;
[...]
ret = bdrv_pread(bs->file, 128 + 4, &s->n_blocks, 4);
[...]
s->n_blocks = be32_to_cpu(s->n_blocks);
/* read offsets */
offsets_size = s->n_blocks * sizeof(uint64_t);
s->offsets = g_malloc(offsets_size);
[...]
for(i=0;i<s->n_blocks;i++) {
s->offsets[i] = be64_to_cpu(s->offsets[i]);
offsets_size can be smaller than n_blocks due to integer overflow.
Therefore s->offsets[] is too small when the for loop byteswaps offsets.
This patch refuses to open files if offsets_size would overflow.
Note that changing the type of offsets_size is not a fix since 32-bit
hosts still only have 32-bit size_t.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
| -rw-r--r-- | block/cloop.c | 7 | ||||
| -rwxr-xr-x | tests/qemu-iotests/075 | 7 | ||||
| -rw-r--r-- | tests/qemu-iotests/075.out | 4 |
3 files changed, 18 insertions, 0 deletions
diff --git a/block/cloop.c b/block/cloop.c index f0216637e1..563e916266 100644 --- a/block/cloop.c +++ b/block/cloop.c @@ -99,6 +99,13 @@ 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)) { + /* Prevent integer overflow */ + error_setg(errp, "n_blocks %u must be %zu or less", + s->n_blocks, + UINT32_MAX / sizeof(uint64_t)); + return -EINVAL; + } offsets_size = s->n_blocks * sizeof(uint64_t); s->offsets = g_malloc(offsets_size); diff --git a/tests/qemu-iotests/075 b/tests/qemu-iotests/075 index 8f54a99b14..9ce6b1fb8c 100755 --- a/tests/qemu-iotests/075 +++ b/tests/qemu-iotests/075 @@ -43,6 +43,7 @@ _supported_proto generic _supported_os Linux block_size_offset=128 +n_blocks_offset=132 echo echo "== check that the first sector can be read ==" @@ -67,6 +68,12 @@ _use_sample_img simple-pattern.cloop.bz2 poke_file "$TEST_IMG" "$block_size_offset" "\xff\xff\xfe\x00" $QEMU_IO -c "read 0 512" $TEST_IMG 2>&1 | _filter_qemu_io | _filter_testdir +echo +echo "== offsets_size overflow ===" +_use_sample_img simple-pattern.cloop.bz2 +poke_file "$TEST_IMG" "$n_blocks_offset" "\xff\xff\xff\xff" +$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 d362c95182..a771789548 100644 --- a/tests/qemu-iotests/075.out +++ b/tests/qemu-iotests/075.out @@ -15,4 +15,8 @@ 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' + +== offsets_size overflow === +qemu-io: can't open device TEST_DIR/simple-pattern.cloop: n_blocks 4294967295 must be 536870911 or less +no file open, try 'help open' *** done |