Re: [Qemu-devel] [PATCH v2 1/1] block/gluster: improve defense over string to int conversion

[Jeff Cody <jcody@redhat.com>]

On Tue, Aug 09, 2016 at 02:20:09PM +0530, Prasanna Kumar Kalever wrote:
> using atoi() for converting string to int may be error prone in case if
> string supplied in the argument is not a fold of numerical number,
> 
> This is not a bug because in the existing code,
> 
> static QemuOptsList runtime_tcp_opts = {
>     .name = "gluster_tcp",
>     .head = QTAILQ_HEAD_INITIALIZER(runtime_tcp_opts.head),
>     .desc = {
>         ...
>         {
>             .name = GLUSTER_OPT_PORT,
>             .type = QEMU_OPT_NUMBER,
>             .help = "port number ...",
>         },
> ...
> };
> 
> port type is QEMU_OPT_NUMBER, before we actually reaches atoi() port is already
> defended by parse_option_number()
> 
> However It is a good practice to use function like parse_uint_full()
> over atoi() to keep port self defended
> 
> Note: As now the port string to int conversion has its defence code set,
> and also we understand that port argument is actually a string type,
> in the follow up patch let's move port type from QEMU_OPT_NUMBER to
> QEMU_OPT_STRING
> 
> Signed-off-by: Prasanna Kumar Kalever <prasanna.kalever@redhat.com>
> ---
> v1: Initial patch
> v2: Address comments on v1 given by Markus
> ---
>  block/gluster.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/block/gluster.c b/block/gluster.c
> index 01b479f..edde1ad 100644
> --- a/block/gluster.c
> +++ b/block/gluster.c
> @@ -14,6 +14,7 @@
>  #include "qapi/qmp/qerror.h"
>  #include "qemu/uri.h"
>  #include "qemu/error-report.h"
> +#include "qemu/cutils.h"
>  
>  #define GLUSTER_OPT_FILENAME        "filename"
>  #define GLUSTER_OPT_VOLUME          "volume"
> @@ -318,6 +319,7 @@ static struct glfs *qemu_gluster_glfs_init(BlockdevOptionsGluster *gconf,
>      int ret;
>      int old_errno;
>      GlusterServerList *server;
> +    unsigned long long port;
>  
>      glfs = glfs_new(gconf->volume);
>      if (!glfs) {
> @@ -330,10 +332,17 @@ static struct glfs *qemu_gluster_glfs_init(BlockdevOptionsGluster *gconf,
>                                     GlusterTransport_lookup[server->value->type],
>                                     server->value->u.q_unix.path, 0);
>          } else {
> +            if ((parse_uint_full(server->value->u.tcp.port, &port, 10) < 0) ||
> +                (port > 65535)) {
> +                error_setg(errp, "'%s' is not a valid port number",
> +                           server->value->u.tcp.port);
> +                errno = EINVAL;

As long as we are range checking, we should probably kick back 0 as an
invalid port number as well, right?

> +                goto out;
> +            }
>              ret = glfs_set_volfile_server(glfs,
>                                     GlusterTransport_lookup[server->value->type],
>                                     server->value->u.tcp.host,
> -                                   atoi(server->value->u.tcp.port));
> +                                   (int)port);
>          }
>  
>          if (ret < 0) {
> -- 
> 2.7.4
>