[Qemu-devel] [PATCH for-2.0 47/47] parallels: Sanity check for s->tracks (CVE-2014-0142)

[Stefan Hajnoczi <stefanha@redhat.com>]

From: Kevin Wolf <kwolf@redhat.com>

This avoids a possible division by zero.

Convert s->tracks to unsigned as well because it feels better than
surviving just because the results of calculations with s->tracks are
converted to unsigned anyway.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/parallels.c          | 7 ++++++-
 tests/qemu-iotests/076     | 7 +++++++
 tests/qemu-iotests/076.out | 4 ++++
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/block/parallels.c b/block/parallels.c
index fe47ecb..1a5bd35 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -51,7 +51,7 @@ typedef struct BDRVParallelsState {
     uint32_t *catalog_bitmap;
     unsigned int catalog_size;
 
-    int tracks;
+    unsigned int tracks;
 } BDRVParallelsState;
 
 static int parallels_probe(const uint8_t *buf, int buf_size, const char *filename)
@@ -93,6 +93,11 @@ static int parallels_open(BlockDriverState *bs, QDict *options, int flags,
     bs->total_sectors = le32_to_cpu(ph.nb_sectors);
 
     s->tracks = le32_to_cpu(ph.tracks);
+    if (s->tracks == 0) {
+        error_setg(errp, "Invalid image: Zero sectors per track");
+        ret = -EINVAL;
+        goto fail;
+    }
 
     s->catalog_size = le32_to_cpu(ph.catalog_entries);
     if (s->catalog_size > INT_MAX / 4) {
diff --git a/tests/qemu-iotests/076 b/tests/qemu-iotests/076
index 6028ac5..b614a7d 100755
--- a/tests/qemu-iotests/076
+++ b/tests/qemu-iotests/076
@@ -42,6 +42,7 @@ _supported_fmt parallels
 _supported_proto generic
 _supported_os Linux
 
+tracks_offset=$((0x1c))
 catalog_entries_offset=$((0x20))
 nb_sectors_offset=$((0x24))
 
@@ -63,6 +64,12 @@ poke_file "$TEST_IMG" "$nb_sectors_offset" "\xff\xff\xff\xff"
 poke_file "$TEST_IMG" "$catalog_entries_offset" "\x01\x00\x00\x40"
 { $QEMU_IO -c "read 64M 64M" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
 
+echo
+echo "== Zero sectors per track =="
+_use_sample_img fake.parallels.bz2
+poke_file "$TEST_IMG" "$tracks_offset" "\x00\x00\x00\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/076.out b/tests/qemu-iotests/076.out
index 12af42a..f7745d8 100644
--- a/tests/qemu-iotests/076.out
+++ b/tests/qemu-iotests/076.out
@@ -11,4 +11,8 @@ no file open, try 'help open'
 == Overflow in catalog allocation ==
 qemu-io: can't open device TEST_DIR/fake.parallels: Catalog too large
 no file open, try 'help open'
+
+== Zero sectors per track ==
+qemu-io: can't open device TEST_DIR/fake.parallels: Invalid image: Zero sectors per track
+no file open, try 'help open'
 *** done
-- 
1.8.5.3