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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: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Kevin Wolf 2014-03-26 13:05:34 +01:00 committed by Stefan Hajnoczi
parent e3737b820b
commit 8e53abbc20
3 changed files with 29 additions and 0 deletions
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8
block/bochs.c
View File

@ -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");

13
tests/qemu-iotests/078
View File

@ -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

8
tests/qemu-iotests/078.out
View File

@ -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