Commit 8e53abbc authored by Kevin Wolf's avatar Kevin Wolf Committed by Stefan Hajnoczi
Browse files

bochs: Check extent_size header field (CVE-2014-0142) 



This fixes two possible division by zero crashes: In bochs_open() and in
seek_to_sector().

Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
Reviewed-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: default avatarMax Reitz <mreitz@redhat.com>
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent e3737b82

block/bochs.c

+8 −0
Original line number Diff line number Diff line
@@ -148,6 +148,14 @@ static int bochs_open(BlockDriverState *bs, QDict *options, int flags, 
    s->extent_blocks = 1 + (le32_to_cpu(bochs.extent) - 1) / 512;



    s->extent_size = le32_to_cpu(bochs.extent);

    if (s->extent_size == 0) {

        error_setg(errp, "Extent size may not be zero");

        return -EINVAL;

    } else if (s->extent_size > 0x800000) {

        error_setg(errp, "Extent size %" PRIu32 " is too large",

                   s->extent_size);

        return -EINVAL;

    }



    if (s->catalog_size < bs->total_sectors / s->extent_size) {

        error_setg(errp, "Catalog size is too small for this disk size");

tests/qemu-iotests/078

+13 −0
Original line number Diff line number Diff line
@@ -43,6 +43,7 @@ _supported_proto generic 
_supported_os Linux



catalog_size_offset=$((0x48))

extent_size_offset=$((0x50))

disk_size_offset=$((0x58))



echo
@@ -68,6 +69,18 @@ _use_sample_img empty.bochs.bz2 
poke_file "$TEST_IMG" "$disk_size_offset" "\x00\xc0\x0f\x00\x00\x00\x00\x7f"

{ $QEMU_IO -c "read 2T 4k" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir



echo

echo "== Negative extent size =="

_use_sample_img empty.bochs.bz2

poke_file "$TEST_IMG" "$extent_size_offset" "\xff\xff\xff\xff"

{ $QEMU_IO -c "read 768k 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir



echo

echo "== Zero extent size =="

_use_sample_img empty.bochs.bz2

poke_file "$TEST_IMG" "$extent_size_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

tests/qemu-iotests/078.out

+8 −0
Original line number Diff line number Diff line
@@ -15,4 +15,12 @@ no file open, try 'help open' 
== Too small catalog bitmap for image size ==

qemu-io: can't open device TEST_DIR/empty.bochs: Catalog size is too small for this disk size

no file open, try 'help open'



== Negative extent size ==

qemu-io: can't open device TEST_DIR/empty.bochs: Extent size 4294967295 is too large

no file open, try 'help open'



== Zero extent size ==

qemu-io: can't open device TEST_DIR/empty.bochs: Extent size may not be zero

no file open, try 'help open'

*** done