Re: [PATCH] block: Fix pad_request's request restriction

[Hanna Czenczek <hreitz@redhat.com>]

On 09.06.23 10:33, Hanna Czenczek wrote:
> bdrv_pad_request() relies on requests' lengths not to exceed SIZE_MAX,
> which bdrv_check_qiov_request() does not guarantee.
>
> bdrv_check_request32() however will guarantee this, and both of
> bdrv_pad_request()'s callers (bdrv_co_preadv_part() and
> bdrv_co_pwritev_part()) already run it before calling
> bdrv_pad_request().  Therefore, bdrv_pad_request() can safely call
> bdrv_check_request32() without expecting error, too.
>
> There is one difference between bdrv_check_qiov_request() and
> bdrv_check_request32(): The former takes an errp, the latter does not,
> so we can no longer just pass &error_abort.  Instead, we need to check
> the returned value.  While we do expect success (because the callers
> have already run this function), an assert(ret == 0) is not much simpler
> than just to return an error if it occurs, so let us handle errors by
> returning them up the stack now.
>
> Reported-by: Peter Maydell <peter.maydell@linaro.org>
> Fixes: 18743311b829cafc1737a5f20bc3248d5f91ee2a
>         ("block: Collapse padded I/O vecs exceeding IOV_MAX")
> Signed-off-by: Hanna Czenczek <hreitz@redhat.com>
> ---
>   block/io.c | 8 ++++++--
>   1 file changed, 6 insertions(+), 2 deletions(-)

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