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bochs: Fix catalog size check

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The old check was off by a factor of 512 and didn't consider cases where
we don't get an exact division. This could lead to an out-of-bounds
array access in seek_to_sector().

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
This commit is contained in:
Kevin Wolf 2014-04-09 12:10:34 +02:00
parent 28ec11bc88
commit 715c3f60ef
3 changed files with 20 additions and 6 deletions
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14
block/bochs.c
View file

@ -148,8 +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");
if (s->extent_size < BDRV_SECTOR_SIZE) {
/* bximage actually never creates extents smaller than 4k */
error_setg(errp, "Extent size must be at least 512");
ret = -EINVAL;
goto fail;
} else if (!is_power_of_2(s->extent_size)) {
error_setg(errp, "Extent size %" PRIu32 " is not a power of two",
s->extent_size);
ret = -EINVAL;
goto fail;
} else if (s->extent_size > 0x800000) {
@ -159,7 +165,9 @@ static int bochs_open(BlockDriverState *bs, QDict *options, int flags,
goto fail;
}
if (s->catalog_size < bs->total_sectors / s->extent_size) {
if (s->catalog_size < DIV_ROUND_UP(bs->total_sectors,
s->extent_size / BDRV_SECTOR_SIZE))
{
error_setg(errp, "Catalog size is too small for this disk size");
ret = -EINVAL;
goto fail;

6
tests/qemu-iotests/078
View file

@ -69,10 +69,14 @@ _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" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
_use_sample_img empty.bochs.bz2
poke_file "$TEST_IMG" "$catalog_size_offset" "\x10\x00\x00\x00"
{ $QEMU_IO -c "read 0xfbe00 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
echo
echo "== Negative extent size =="
_use_sample_img empty.bochs.bz2
poke_file "$TEST_IMG" "$extent_size_offset" "\xff\xff\xff\xff"
poke_file "$TEST_IMG" "$extent_size_offset" "\x00\x00\x00\x80"
{ $QEMU_IO -c "read 768k 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
echo

6
tests/qemu-iotests/078.out
View file

@ -15,12 +15,14 @@ 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'
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
qemu-io: can't open device TEST_DIR/empty.bochs: Extent size 2147483648 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
qemu-io: can't open device TEST_DIR/empty.bochs: Extent size must be at least 512
no file open, try 'help open'
*** done