Commit 9877860e authored by Peter Maydell's avatar Peter Maydell Committed by Kevin Wolf
Browse files

block/vmdk: Report failures in vmdk_read_cid() 



The function vmdk_read_cid() can fail if the read on the underlying
block device fails, or if there's a format error in the VMDK file.
However its API doesn't provide a mechanism to report these errors,
and in some cases we were returning a CID of 0 and in some cases a
CID of 0xffffffff, either of which might potentially be valid values.

Change the function to return 0 on success or a negative errno, and
return the CID via a uint32_t* argument. Update the callsites to
handle and propagate the error appropriately.

This fixes in passing a Coverity-spotted issue (CID 1350038) where
we weren't checking the return value from sscanf().

Signed-off-by: default avatarPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: default avatarFam Zheng <famz@redhat.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent 27e4cf13

block/vmdk.c

+32 −12
Original line number Diff line number Diff line
@@ -242,10 +242,11 @@ static void vmdk_free_last_extent(BlockDriverState *bs) 
    s->extents = g_renew(VmdkExtent, s->extents, s->num_extents);

}



static uint32_t vmdk_read_cid(BlockDriverState *bs, int parent)

/* Return -ve errno, or 0 on success and write CID into *pcid. */

static int vmdk_read_cid(BlockDriverState *bs, int parent, uint32_t *pcid)

{

    char *desc;

    uint32_t cid = 0xffffffff;

    uint32_t cid;

    const char *p_name, *cid_str;

    size_t cid_str_size;

    BDRVVmdkState *s = bs->opaque;
@@ -254,8 +255,7 @@ static uint32_t vmdk_read_cid(BlockDriverState *bs, int parent) 
    desc = g_malloc0(DESC_SIZE);

    ret = bdrv_pread(bs->file, s->desc_offset, desc, DESC_SIZE);

    if (ret < 0) {

        g_free(desc);

        return 0;

        goto out;

    }



    if (parent) {
@@ -268,13 +268,21 @@ static uint32_t vmdk_read_cid(BlockDriverState *bs, int parent) 


    desc[DESC_SIZE - 1] = '\0';

    p_name = strstr(desc, cid_str);

    if (p_name != NULL) {

    if (p_name == NULL) {

        ret = -EINVAL;

        goto out;

    }

    p_name += cid_str_size;

        sscanf(p_name, "%" SCNx32, &cid);

    if (sscanf(p_name, "%" SCNx32, &cid) != 1) {

        ret = -EINVAL;

        goto out;

    }

    *pcid = cid;

    ret = 0;



out:

    g_free(desc);

    return cid;

    return ret;

}



static int vmdk_write_cid(BlockDriverState *bs, uint32_t cid)
@@ -322,7 +330,10 @@ static int vmdk_is_cid_valid(BlockDriverState *bs) 
    if (!s->cid_checked && bs->backing) {

        BlockDriverState *p_bs = bs->backing->bs;



        cur_pcid = vmdk_read_cid(p_bs, 0);

        if (vmdk_read_cid(p_bs, 0, &cur_pcid) != 0) {

            /* read failure: report as not valid */

            return 0;

        }

        if (s->parent_cid != cur_pcid) {

            /* CID not valid */

            return 0;
@@ -975,8 +986,14 @@ static int vmdk_open(BlockDriverState *bs, QDict *options, int flags, 
    if (ret) {

        goto fail;

    }

    s->cid = vmdk_read_cid(bs, 0);

    s->parent_cid = vmdk_read_cid(bs, 1);

    ret = vmdk_read_cid(bs, 0, &s->cid);

    if (ret) {

        goto fail;

    }

    ret = vmdk_read_cid(bs, 1, &s->parent_cid);

    if (ret) {

        goto fail;

    }

    qemu_co_mutex_init(&s->lock);



    /* Disable migration when VMDK images are used */
@@ -2008,8 +2025,11 @@ static int vmdk_create(const char *filename, QemuOpts *opts, Error **errp) 
            ret = -EINVAL;

            goto exit;

        }

        parent_cid = vmdk_read_cid(blk_bs(blk), 0);

        ret = vmdk_read_cid(blk_bs(blk), 0, &parent_cid);

        blk_unref(blk);

        if (ret) {

            goto exit;

        }

        snprintf(parent_desc_line, BUF_SIZE,

                "parentFileNameHint=\"%s\"", backing_file);

    }