Am 02.09.2019 um 17:24 hat Peter Lieven geschrieben:
> qemu is currently not able to detect truncated vhdx image files.
> Add a basic check if all allocated blocks are reachable at open and
> report all errors during bdrv_co_check.
>
> Signed-off-by: Peter Lieven <p...@kamp.de>
> ---
> V2: - add error reporting [Kevin]
> - use bdrv_getlength instead of bdrv_get_allocated_file_size [Kevin]
> - factor out BAT entry check and add error reporting for region
> overlaps
> - already check on vhdx_open
>
> block/vhdx.c | 85 +++++++++++++++++++++++++++++++++++++++++-----------
> 1 file changed, 68 insertions(+), 17 deletions(-)
>
> diff --git a/block/vhdx.c b/block/vhdx.c
> index 6a09d0a55c..6afba5e8c2 100644
> --- a/block/vhdx.c
> +++ b/block/vhdx.c
> @@ -24,6 +24,7 @@
> #include "qemu/option.h"
> #include "qemu/crc32c.h"
> #include "qemu/bswap.h"
> +#include "qemu/error-report.h"
> #include "vhdx.h"
> #include "migration/blocker.h"
> #include "qemu/uuid.h"
> @@ -235,6 +236,9 @@ static int vhdx_region_check(BDRVVHDXState *s, uint64_t
> start, uint64_t length)
> end = start + length;
> QLIST_FOREACH(r, &s->regions, entries) {
> if (!((start >= r->end) || (end <= r->start))) {
> + error_report("VHDX region %" PRIu64 "-%" PRIu64 " overlaps with "
> + "region %" PRIu64 "-%." PRIu64, start, end,
> r->start,
> + r->end);
> ret = -EINVAL;
> goto exit;
> }
> @@ -877,6 +881,60 @@ static void vhdx_calc_bat_entries(BDRVVHDXState *s)
>
> }
>
> +static int vhdx_check_bat_entries(BlockDriverState *bs, int *errcnt)
> +{
> + BDRVVHDXState *s = bs->opaque;
> + int64_t image_file_size = bdrv_getlength(bs->file->bs);
> + uint64_t payblocks = s->chunk_ratio;
> + int i, ret = 0;
bdrv_getlength() can fail. It's probably better to error out immediately
instead of reporting that every BAT entry is > -1.
> + for (i = 0; i < s->bat_entries; i++) {
s->bat_entries is uint32_t, so i should probably be the same.
> + if ((s->bat[i] & VHDX_BAT_STATE_BIT_MASK) ==
> + PAYLOAD_BLOCK_FULLY_PRESENT) {
> + /*
> + * Check if fully allocated BAT entries do not reside after
> + * end of the image file.
> + */
> + if ((s->bat[i] & VHDX_BAT_FILE_OFF_MASK) + s->block_size >
> + image_file_size) {
Didn't we want to introduce an overflow check before making this check?
Something like if (bat_offset > UINT64_MAX - s->block_size)?
> + error_report("VHDX BAT entry %d offset points after end of "
> + "file. Image has probably been truncated.", i);
> + ret = -EINVAL;
> + if (!errcnt) {
> + break;
> + }
> + (*errcnt)++;
> + }
> +
> + /*
> + * verify populated BAT field file offsets against
> + * region table and log entries
> + */
> + if (payblocks--) {
> + /* payload bat entries */
> + int ret2;
> + ret2 = vhdx_region_check(s, s->bat[i] &
> VHDX_BAT_FILE_OFF_MASK,
> + s->block_size);
> + if (ret2 < 0) {
> + ret = -EINVAL;
> + if (errcnt) {
This one you already noticed yourself.
> + break;
> + }
> + (*errcnt)++;
> + }
> + } else {
> + payblocks = s->chunk_ratio;
> + /*
> + * Once differencing files are supported, verify sector
> bitmap
> + * blocks here
> + */
> + }
> + }
> + }
> +
> + return ret;
> +}
The rest looks good to me.
Kevin
