On Mon, Oct 12, 2020 at 12:57:11PM +0100, Ferruh Yigit wrote:
> On 10/1/2020 6:09 PM, Kevin Laatz wrote:
> > Add a check for the return value of the sscanf call in
> > parse_internal_args(), returning an error if we don't get the expected
> > result.
> >
> > Coverity issue: 362049
> > Fixes: 96cb19521147 ("net/ring: use EAL APIs in PMD specific API")
> > Cc: sta...@dpdk.org
> >
> > Signed-off-by: Kevin Laatz <kevin.la...@intel.com>
> >
> > ---
> > v2: added consumed characters count check
> > ---
> > drivers/net/ring/rte_eth_ring.c | 7 ++++++-
> > 1 file changed, 6 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/ring/rte_eth_ring.c
> > b/drivers/net/ring/rte_eth_ring.c
> > index 40fe1ca4ba..66367465fd 100644
> > --- a/drivers/net/ring/rte_eth_ring.c
> > +++ b/drivers/net/ring/rte_eth_ring.c
> > @@ -538,8 +538,13 @@ parse_internal_args(const char *key __rte_unused,
> > const char *value,
> > {
> > struct ring_internal_args **internal_args = data;
> > void *args;
> > + int n;
> > - sscanf(value, "%p", &args);
> > + if (sscanf(value, "%p%n", &args, &n) != 1 || (size_t)n !=
> > strlen(value)) {
>
> two small details,
>
> 1- I see following note in the sscanf manual:
> https://linux.die.net/man/3/sscanf
> "
> The C standard says: "Execution of a %n directive does not increment the
> assignment count returned at the completion of execution" but the
> Corrigendum seems to contradict this. Probably it is wise not to make any
> assumptions on the effect of %n conversions on the return value.
> "
>
> So what do you think checking return value as " == 0" ?
>
Maybe in that copy of the man page but on my Ubuntu system there is no such
disclaimer, and I don't see it either on the kernel.org man page reference:
https://man7.org/linux/man-pages/man3/sscanf.3.html
That official man page reference clearly states that the behaviour is that
%n does not increase the reference count.
