Re: [Qemu-devel] [PATCH 2/6] sheepdog: fix possible resouce leak and out-of-bounds access

[Paolo Bonzini <pbonzini@redhat.com>]

On 03/03/2016 10:43, Gonglei wrote:
> CID 1352418 (#1 of 1): Out-of-bounds access (INCOMPATIBLE_CAST)
> incompatible_cast: Pointer &snap_id points to an object whose effective
> type is unsigned int (32 bits, unsigned) but is dereferenced as a wider
> unsigned long (64 bits, unsigned). This may lead to memory corruption.
> 
> We also need to free local_err when ret is not equals to 0.
> 
> Signed-off-by: Gonglei <arei.gonglei@huawei.com>
> ---
>  block/sheepdog.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/block/sheepdog.c b/block/sheepdog.c
> index 8739acc..3d81bba 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;
> @@ -2565,20 +2565,23 @@ 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)) {
> +    if (qemu_strtoul(snapshot_id, NULL, 10, &snap_id)) {
>          return -1;
>      }
>  
>      if (snap_id) {
> +        assert(snap_id <= UINT_MAX);
> +
>          hdr.snapid = snap_id;
>      } else {
>          pstrcpy(snap_tag, sizeof(snap_tag), snapshot_id);
>          pstrcpy(buf + SD_MAX_VDI_LEN, SD_MAX_VDI_TAG_LEN, snap_tag);
>      }
>  
> -    ret = find_vdi_name(s, s->name, snap_id, snap_tag, &vid, true,
> +    ret = find_vdi_name(s, s->name, hdr.snapid, snap_tag, &vid, true,
>                          &local_err);
>      if (ret) {
> +        error_report_err(local_err);
>          return ret;
>      }
>  
> 

A patch for this has been posted yesterday by Jeff Cody.

Paolo