[LTP] [PATCH v2] tst_kconfig: Avoid reporting buffer overflow when parsing /proc/cmdline

[Li Wang]

On Thu, Jun 20, 2024 at 1:21 PM Petr Vorel <pvorel@suse.cz> wrote:

> >  Li Wang <liwang@redhat.com> wrote:
>
> > When the test is run with a kernel booting with many parameters, the
> > > buffer size is often not large enough to store the complete command
> > > line. This results in a buffer overflow and the test complains with
> > > the following message:
>
> > >   tst_kconfig.c:609: TWARN: Buffer overflowed while parsing
> /proc/cmdline
>
> > > Note:
>
> > > Petr point out that these configs, which are generated by toolchain
> will
> > > be longer than 128 chars someday, but I don't think that is the reason
> > > we need raise our parsed buffer, since tst_kcmdline_parse() was just
> add
> > > for popular parameter (which always pass by user and short). So far I
> > > don't see any LTP test parse a longer parameters.
>
> > > Fixes: 180834982 ("kconfig: add funtion to parse /proc/cmdline")
> > > Signed-off-by: Li Wang <liwang@redhat.com>
> > > Cc: Petr Vorel <pvorel@suse.cz>
> > > ---
> > >  include/tst_kconfig.h | 2 +-
> > >  lib/tst_kconfig.c     | 4 ++--
> > >  2 files changed, 3 insertions(+), 3 deletions(-)
>
> > > diff --git a/include/tst_kconfig.h b/include/tst_kconfig.h
> > > index dcb370574..23f807409 100644
> > > --- a/include/tst_kconfig.h
> > > +++ b/include/tst_kconfig.h
> > > @@ -87,7 +87,7 @@ int tst_kconfig_check(const char *const kconfigs[]);
> > >   */
> > >  struct tst_kcmdline_var {
> > >         const char *key;
> > > -       char value[128];
> > > +       char value[256];
> > >         bool found;
> > >  };
>
> > > diff --git a/lib/tst_kconfig.c b/lib/tst_kconfig.c
> > > index e16ca1400..8eb1b803f 100644
> > > --- a/lib/tst_kconfig.c
> > > +++ b/lib/tst_kconfig.c
> > > @@ -569,7 +569,7 @@ char tst_kconfig_get(const char *confname)
>
> > >  void tst_kcmdline_parse(struct tst_kcmdline_var params[], size_t
> > > params_len)
> > >  {
> > > -       char buf[128], line[512];
> > > +       char buf[256], line[512];
>
>
> > Petr, if you are still worried, feel free to enlarge them to char
> > 'buf[512], line[2048];' during merge :).
>
> Li, I'm ok with 256 :).
> Reviewed-by: Petr Vorel <pvorel@suse.cz>
>

Thanks.


> -                               tst_res(TWARN, "Buffer overflowed while
> parsing /proc/cmdline");
> +                               tst_res(TINFO, "Buffer overflowed while
> parsing /proc/cmdline");
>
>

> But I wonder if we should keep TWARN. Or at least add
> +                               tst_res(TINFO, "WARNING: Buffer overflowed
> while parsing /proc/cmdline");
>

+1, I'd merge like this if Cyril has no more comments.


-- 
Regards,
Li Wang