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[Qemu-devel] [PATCH for-2.0 06/47] block/cloop: refuse images with bogus
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PATCH for-2.0 06/47] block/cloop: refuse images with bogus offsets (CVE-2014-0144) |
Date: |
Wed, 26 Mar 2014 13:05:28 +0100 |
The offsets[] array allows efficient seeking and tells us the maximum
compressed data size. If the offsets are bogus the maximum compressed
data size will be unrealistic.
This could cause g_malloc() to abort and bogus offsets mean the image is
broken anyway. Therefore we should refuse such images.
Signed-off-by: Stefan Hajnoczi <address@hidden>
Signed-off-by: Kevin Wolf <address@hidden>
---
block/cloop.c | 34 +++++++++++++++++++++++++++++-----
tests/qemu-iotests/075 | 15 +++++++++++++++
tests/qemu-iotests/075.out | 8 ++++++++
3 files changed, 52 insertions(+), 5 deletions(-)
diff --git a/block/cloop.c b/block/cloop.c
index 844665e..55a804f 100644
--- a/block/cloop.c
+++ b/block/cloop.c
@@ -124,12 +124,36 @@ static int cloop_open(BlockDriverState *bs, QDict
*options, int flags,
}
for(i=0;i<s->n_blocks;i++) {
+ uint64_t size;
+
s->offsets[i] = be64_to_cpu(s->offsets[i]);
- if (i > 0) {
- uint32_t size = s->offsets[i] - s->offsets[i - 1];
- if (size > max_compressed_block_size) {
- max_compressed_block_size = size;
- }
+ if (i == 0) {
+ continue;
+ }
+
+ if (s->offsets[i] < s->offsets[i - 1]) {
+ error_setg(errp, "offsets not monotonically increasing at "
+ "index %u, image file is corrupt", i);
+ ret = -EINVAL;
+ goto fail;
+ }
+
+ size = s->offsets[i] - s->offsets[i - 1];
+
+ /* Compressed blocks should be smaller than the uncompressed block size
+ * but maybe compression performed poorly so the compressed block is
+ * actually bigger. Clamp down on unrealistic values to prevent
+ * ridiculous s->compressed_block allocation.
+ */
+ if (size > 2 * MAX_BLOCK_SIZE) {
+ error_setg(errp, "invalid compressed block size at index %u, "
+ "image file is corrupt", i);
+ ret = -EINVAL;
+ goto fail;
+ }
+
+ if (size > max_compressed_block_size) {
+ max_compressed_block_size = size;
}
}
diff --git a/tests/qemu-iotests/075 b/tests/qemu-iotests/075
index 9c00fa8..d74fb33 100755
--- a/tests/qemu-iotests/075
+++ b/tests/qemu-iotests/075
@@ -44,6 +44,7 @@ _supported_os Linux
block_size_offset=128
n_blocks_offset=132
+offsets_offset=136
echo
echo "== check that the first sector can be read =="
@@ -80,6 +81,20 @@ _use_sample_img simple-pattern.cloop.bz2
poke_file "$TEST_IMG" "$n_blocks_offset" "\x04\x00\x00\x01"
$QEMU_IO -c "read 0 512" $TEST_IMG 2>&1 | _filter_qemu_io | _filter_testdir
+echo
+echo "== refuse images with non-monotonically increasing offsets =="
+_use_sample_img simple-pattern.cloop.bz2
+poke_file "$TEST_IMG" "$offsets_offset" "\x00\x00\x00\x00\xff\xff\xff\xff"
+poke_file "$TEST_IMG" $((offsets_offset + 8))
"\x00\x00\x00\x00\xff\xfe\x00\x00"
+$QEMU_IO -c "read 0 512" $TEST_IMG 2>&1 | _filter_qemu_io | _filter_testdir
+
+echo
+echo "== refuse images with invalid compressed block size =="
+_use_sample_img simple-pattern.cloop.bz2
+poke_file "$TEST_IMG" "$offsets_offset" "\x00\x00\x00\x00\x00\x00\x00\x00"
+poke_file "$TEST_IMG" $((offsets_offset + 8))
"\xff\xff\xff\xff\xff\xff\xff\xff"
+$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 7cdaee1..911cd3b 100644
--- a/tests/qemu-iotests/075.out
+++ b/tests/qemu-iotests/075.out
@@ -23,4 +23,12 @@ no file open, try 'help open'
== refuse images that require too many offsets ===
qemu-io: can't open device TEST_DIR/simple-pattern.cloop: image requires too
many offsets, try increasing block size
no file open, try 'help open'
+
+== refuse images with non-monotonically increasing offsets ==
+qemu-io: can't open device TEST_DIR/simple-pattern.cloop: offsets not
monotonically increasing at index 1, image file is corrupt
+no file open, try 'help open'
+
+== refuse images with invalid compressed block size ==
+qemu-io: can't open device TEST_DIR/simple-pattern.cloop: invalid compressed
block size at index 1, image file is corrupt
+no file open, try 'help open'
*** done
--
1.8.5.3
- [Qemu-devel] [PATCH for-2.0 02/47] qemu-iotests: add cloop input validation tests, (continued)
- [Qemu-devel] [PATCH for-2.0 02/47] qemu-iotests: add cloop input validation tests, Stefan Hajnoczi, 2014/03/26
- [Qemu-devel] [PATCH for-2.0 01/47] qemu-iotests: add ./check -cloop support, Stefan Hajnoczi, 2014/03/26
- [Qemu-devel] [PATCH for-2.0 03/47] block/cloop: validate block_size header field (CVE-2014-0144), Stefan Hajnoczi, 2014/03/26
- [Qemu-devel] [PATCH for-2.0 04/47] block/cloop: prevent offsets_size integer overflow (CVE-2014-0143), Stefan Hajnoczi, 2014/03/26
- [Qemu-devel] [PATCH for-2.0 05/47] block/cloop: refuse images with huge offsets arrays (CVE-2014-0144), Stefan Hajnoczi, 2014/03/26
- [Qemu-devel] [PATCH for-2.0 06/47] block/cloop: refuse images with bogus offsets (CVE-2014-0144),
Stefan Hajnoczi <=
- [Qemu-devel] [PATCH for-2.0 08/47] qemu-iotests: Support for bochs format, Stefan Hajnoczi, 2014/03/26
- [Qemu-devel] [PATCH for-2.0 07/47] block/cloop: fix offsets[] size off-by-one, Stefan Hajnoczi, 2014/03/26
- [Qemu-devel] [PATCH for-2.0 09/47] bochs: Unify header structs and make them QEMU_PACKED, Stefan Hajnoczi, 2014/03/26
- [Qemu-devel] [PATCH for-2.0 10/47] bochs: Use unsigned variables for offsets and sizes (CVE-2014-0147), Stefan Hajnoczi, 2014/03/26
- [Qemu-devel] [PATCH for-2.0 11/47] bochs: Check catalog_size header field (CVE-2014-0143), Stefan Hajnoczi, 2014/03/26