[PATCH] env: mmc: Correct partition comparison in mmc_offset_try_partition

[Hoyeonjiki Kim]

On Thu, Nov 12, 2020 at 8:34 AM Jaehoon Chung <jh80.chung at samsung.com> wrote:
>
> Hi,
>
> On 11/11/20 7:25 PM, 김호연지기 wrote:
> > On Wed, Nov 11, 2020 at 7:07 PM Jorge Ramirez-Ortiz, Gmail
> > <jorge.ramirez.ortiz at gmail.com> wrote:
> >>
> >> On 11/11/20, Jaehoon Chung wrote:
> >>> On 11/10/20 11:28 PM, Hoyeonjiki Kim wrote:
> >>>> The function mmc_offset_try_partition searches MMC partition to save the
> >>>> environment data by name.  However, it only compares the first word-size
> >>>> bytes (size of 'const char *'), which may make the function to find
> >>>> unintended partition.
> >>>>
> >>>> Correct the function not to partially compare the partition name with
> >>>> config "u-boot,,mmc-env-partition".
> >>>>
> >>>> Signed-off-by: Hoyeonjiki Kim <jigi.kim at gmail.com>
> >>>> ---
> >>>>  env/mmc.c | 2 +-
> >>>>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>>>
> >>>> diff --git a/env/mmc.c b/env/mmc.c
> >>>> index 4e67180b23..505f7aa2b8 100644
> >>>> --- a/env/mmc.c
> >>>> +++ b/env/mmc.c
> >>>> @@ -42,7 +42,7 @@ static inline int mmc_offset_try_partition(const char *str, int copy, s64 *val)
> >>>>             if (ret < 0)
> >>>>                     return ret;
> >>>>
> >>>> -           if (!strncmp((const char *)info.name, str, sizeof(str)))
> >>>> +           if (!strcmp((const char *)info.name, str))
> >>>
> >>> Using "strlen(str)" is better than changing to strcmp.
> >>>
> >>> strncmp(..., ..., strlen(str))
> >>
> >> absolutely.
> >> maybe also modify the commit like to indicate a fix to the current bug?
> >
> > Thanks for the feedback for both.
> >
> > However, when we do so, isn't there still the possibility for the
> > function searching incorrect partition if,
> > 1) "str" is shorter than "info.name", and
> > 2) the first "strlen(str)" letters of "info.name" is same with those of "str"?
>
> Make sense. You're right. :)
>
> There are two approach. One is that choose one of those length what is longer.
> Other is your approach. I don't have any objection to fix whatever.
>
> Just resend your patch with Jorge's comment, plz.
>
>
> Best Regards,
> Jaehoon Chung

Sure, thanks for your opinion.
Will be back with v2.

Best Regards,
Hoyeonjiki Kim

>
> >
> > This commit is for fixing the current bug, but also I wanna make sure
> > that partition name matches fully.
> >
> > Let me know your opinion.
> >
> > Best Regards,
> > Hoeyonjiki Kim
> >
> >>
> >>>
> >>>
> >>> Best Regards,
> >>> Jaehoon Chung
> >>>
> >>>>                     break;
> >>>>     }
> >>>>
> >>>>
> >>>
> >
>