Re: [Qemu-devel] [PATCH] block/curl: Improve type safety of s->timeout.

[Laszlo Ersek <lersek@redhat.com>]

On 10/06/14 16:32, Richard W.M. Jones wrote:
> qemu_opt_get_number returns a uint64_t, and curl_easy_setopt expects a
> long (not an int).
> 
> Store the timeout (which is a positive number of seconds) as a
> uint64_t.  Check that the number given by the user is reasonable.
> Cast it to long before calling curl_easy_setopt.
> 
> Example error message after this change has been applied:
> 
> $ ./qemu-img create -f qcow2 /tmp/test.qcow2 \
>     -b 'json: { "file.driver":"https",
>                 "file.url":"https://foo/bar",
>                 "file.timeout":-1 }'
> qemu-img: /tmp/test.qcow2: Could not open 'json: { "file.driver":"https", "file.url":"https://foo/bar", "file.timeout":-1 }': timeout parameter is too large or negative: Invalid argument
> 
> Signed-off-by: Richard W.M. Jones <rjones@redhat.com>
> ---
>  block/curl.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/block/curl.c b/block/curl.c
> index 225407c..5233ff6 100644
> --- a/block/curl.c
> +++ b/block/curl.c
> @@ -112,7 +112,7 @@ typedef struct BDRVCURLState {
>      char *url;
>      size_t readahead_size;
>      bool sslverify;
> -    int timeout;
> +    uint64_t timeout;
>      char *cookie;
>      bool accept_range;
>      AioContext *aio_context;
> @@ -390,7 +390,7 @@ static CURLState *curl_init_state(BlockDriverState *bs, BDRVCURLState *s)
>          if (s->cookie) {
>              curl_easy_setopt(state->curl, CURLOPT_COOKIE, s->cookie);
>          }
> -        curl_easy_setopt(state->curl, CURLOPT_TIMEOUT, s->timeout);
> +        curl_easy_setopt(state->curl, CURLOPT_TIMEOUT, (long)s->timeout);
>          curl_easy_setopt(state->curl, CURLOPT_WRITEFUNCTION,
>                           (void *)curl_read_cb);
>          curl_easy_setopt(state->curl, CURLOPT_WRITEDATA, (void *)state);
> @@ -546,6 +546,10 @@ static int curl_open(BlockDriverState *bs, QDict *options, int flags,
>  
>      s->timeout = qemu_opt_get_number(opts, CURL_BLOCK_OPT_TIMEOUT,
>                                       CURL_TIMEOUT_DEFAULT);
> +    if (s->timeout > 100000) {
> +        error_setg(errp, "timeout parameter is too large or negative");
> +        goto out_noclean;
> +    }
>  
>      s->sslverify = qemu_opt_get_bool(opts, CURL_BLOCK_OPT_SSLVERIFY, true);
>  
> 

Since we're validating s->timeout -- is a zero value okay?

Thanks
Laszlo