Re: [Qemu-devel] [PATCH v3 1/1] block/sheepdog: fix argument passed to qemu_strtoul()

[Max Reitz <mreitz@redhat.com>]

[-- Attachment #1.1: Type: text/plain, Size: 2114 bytes --]

On 02.03.2016 17:24, Jeff Cody wrote:
> The function qemu_strtoul() reads 'unsigned long' sized data,
> which is larger than uint32_t on 64-bit machines.
> 
> Even though the snap_id field in the header is 32-bits, we must
> accomodate the full size in qemu_strtoul().
> 
> This patch also adds more meaningful error handling to the
> qemu_strtoul() call, and subsequent results.
> 
> Reported-by: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Jeff Cody <jcody@redhat.com>
> ---
>  block/sheepdog.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/block/sheepdog.c b/block/sheepdog.c
> index 8739acc..87f0027 100644
> --- a/block/sheepdog.c
> +++ b/block/sheepdog.c
> @@ -2543,7 +2543,7 @@ static int sd_snapshot_delete(BlockDriverState *bs,
>                                const char *name,
>                                Error **errp)
>  {
> -    uint32_t snap_id = 0;
> +    unsigned long snap_id = 0;
>      char snap_tag[SD_MAX_VDI_TAG_LEN];
>      Error *local_err = NULL;
>      int fd, ret;
> @@ -2565,12 +2565,15 @@ static int sd_snapshot_delete(BlockDriverState *bs,
>      memset(buf, 0, sizeof(buf));
>      memset(snap_tag, 0, sizeof(snap_tag));
>      pstrcpy(buf, SD_MAX_VDI_LEN, s->name);
> -    if (qemu_strtoul(snapshot_id, NULL, 10, (unsigned long *)&snap_id)) {
> -        return -1;
> +    ret = qemu_strtoul(snapshot_id, NULL, 10, &snap_id);
> +    if (ret || snap_id > UINT32_MAX) {
> +        error_setg(errp, "Invalid snapshot ID: %s",
> +                         snapshot_id ? snapshot_id : "<null>");
> +        return -EINVAL;
>      }
>  
>      if (snap_id) {
> -        hdr.snapid = snap_id;
> +        hdr.snapid = (uint32_t) snap_id;

BTW, not so sure why you are doing an explicit cast to uint32_t here but
not in the call to find_vdi_name() below. But I'll spare you a v4 :-)

Reviewed-by: Max Reitz <mreitz@redhat.com>

>      } else {
>          pstrcpy(snap_tag, sizeof(snap_tag), snapshot_id);
>          pstrcpy(buf + SD_MAX_VDI_LEN, SD_MAX_VDI_TAG_LEN, snap_tag);
> 



[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 473 bytes --]