On Fri, Apr 3, 2020 at 12:43 PM Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
>
> On 4/3/20 8:13 AM, Alain Michaud wrote:
> > Hi Guenter/Marcel,
> >
> >
> > On Fri, Apr 3, 2020 at 11:03 AM Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
> >>
> >> Some static checker run by 0day reports a variableScope warning.
> >>
> >> net/bluetooth/smp.c:870:6: warning:
> >> The scope of the variable 'err' can be reduced. [variableScope]
> >>
> >> There is no need for two separate variables holding return values.
> >> Stick with the existing variable. While at it, don't pre-initialize
> >> 'ret' because it is set in each code path.
> >>
> >> tk_request() is supposed to return a negative error code on errors,
> >> not a bluetooth return code. The calling code converts the return
> >> value to SMP_UNSPECIFIED if needed.
> >>
> >> Fixes: 92516cd97fd4 ("Bluetooth: Always request for user confirmation for Just Works")
> >> Cc: Sonny Sasaka <sonnysasaka@xxxxxxxxxxxx>
> >> Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> >> ---
> >> net/bluetooth/smp.c | 9 ++++-----
> >> 1 file changed, 4 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/net/bluetooth/smp.c b/net/bluetooth/smp.c
> >> index d0b695ee49f6..30e8626dd553 100644
> >> --- a/net/bluetooth/smp.c
> >> +++ b/net/bluetooth/smp.c
> >> @@ -854,8 +854,7 @@ static int tk_request(struct l2cap_conn *conn, u8 remote_oob, u8 auth,
> >> struct l2cap_chan *chan = conn->smp;
> >> struct smp_chan *smp = chan->data;
> >> u32 passkey = 0;
> >> - int ret = 0;
> >> - int err;
> >> + int ret;
> >>
> >> /* Initialize key for JUST WORKS */
> >> memset(smp->tk, 0, sizeof(smp->tk));
> >> @@ -887,12 +886,12 @@ static int tk_request(struct l2cap_conn *conn, u8 remote_oob, u8 auth,
> >> /* If Just Works, Continue with Zero TK and ask user-space for
> >> * confirmation */
> >> if (smp->method == JUST_WORKS) {
> >> - err = mgmt_user_confirm_request(hcon->hdev, &hcon->dst,
> >> + ret = mgmt_user_confirm_request(hcon->hdev, &hcon->dst,
> >> hcon->type,
> >> hcon->dst_type,
> >> passkey, 1);
> >> - if (err)
> >> - return SMP_UNSPECIFIED;
> >> + if (ret)
> >> + return ret;
> > I think there may be some miss match between expected types of error
> > codes here. The SMP error code type seems to be expected throughout
> > this code base, so this change would propagate a potential negative
> > value while the rest of the SMP protocol expects strictly positive
> > error codes.
> >
>
> Up to the patch introducing the SMP_UNSPECIFIED return value, tk_request()
> returned negative error codes, and all callers convert it to SMP_UNSPECIFIED.
>
> If tk_request() is supposed to return SMP_UNSPECIFIED on error, it should
> be returned consistently, and its callers don't have to convert it again.
Agreed, the conventions aren't clear here. I'll differ to Marcel to
provide guidance in this case where as a long term solution might
increase the scope of this patch beyond what would be reasonable.
>
> Guenter
>
> >> set_bit(SMP_FLAG_WAIT_USER, &smp->flags);
> >> return 0;
> >> }
> >> --
> >> 2.17.1
> >>
> >
> > Thanks,
> > Alain
> >
>
