dns_resolver: assure that dns_query() result is null-terminated

dns_query() credulously assumes that keys are null-terminated and
returns a copy of a memory block that is off by one.
---
 net/dns_resolver/dns_query.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

On Sat, Jun 7, 2014 at 1:56 PM, Manuel Schölling
<manuel.schoelling@gmx.de> wrote:
> dns_query() credulously assumes that keys are null-terminated and
> returns a copy of a memory block that is off by one.
> ---
>  net/dns_resolver/dns_query.c |    4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/net/dns_resolver/dns_query.c b/net/dns_resolver/dns_query.c
> index e7b6d53..53be635 100644
> --- a/net/dns_resolver/dns_query.c
> +++ b/net/dns_resolver/dns_query.c
> @@ -149,7 +149,9 @@ int dns_query(const char *type, const char *name, size_t namelen,
>         if (!*_result)
>                 goto put;
>
> -       memcpy(*_result, upayload->data, len + 1);
> +       memcpy(*_result, upayload->data, len);
> +       *_result[len+1] = '\0';

Off by one...

> +
>         if (_expiry)
>                 *_expiry = rkey->expiry;
>
> --
> 1.7.10.4
>
> --
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LOL, that was stupid!
Sorry, I'll send a corrected version in a second...

On Sa, 2014-06-07 at 14:54 -0400, Trond Myklebust wrote:
> On Sat, Jun 7, 2014 at 1:56 PM, Manuel Schölling
> <manuel.schoelling@gmx.de> wrote:
> > dns_query() credulously assumes that keys are null-terminated and
> > returns a copy of a memory block that is off by one.
> > ---
> >  net/dns_resolver/dns_query.c |    4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/net/dns_resolver/dns_query.c b/net/dns_resolver/dns_query.c
> > index e7b6d53..53be635 100644
> > --- a/net/dns_resolver/dns_query.c
> > +++ b/net/dns_resolver/dns_query.c
> > @@ -149,7 +149,9 @@ int dns_query(const char *type, const char *name, size_t namelen,
> >         if (!*_result)
> >                 goto put;
> >
> > -       memcpy(*_result, upayload->data, len + 1);
> > +       memcpy(*_result, upayload->data, len);
> > +       *_result[len+1] = '\0';
> 
> Off by one...
> 
> > +
> >         if (_expiry)
> >                 *_expiry = rkey->expiry;
> >
> > --
> > 1.7.10.4
> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > Please read the FAQ at  http://www.tux.org/lkml/
> 
> 
> 


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