Re: [PATCH v2] proc: Remove empty line in /proc/self/status

[Guenter Roeck <groeck@google.com>]

On Mon, Jan 14, 2019 at 10:50 AM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Mon, Jan 14, 2019 at 10:21:45AM -0800, Guenter Roeck wrote:
> > On Mon, Jan 14, 2019 at 10:13 AM Gwendal Grignou <gwendal@chromium.org> wrote:
> > >
> > > Prevent an empty line in /proc/self/status, allow iotop to work.
> > >
> > > iotop does not like empty lines, fails with:
> > >   File "/usr/local/lib64/python2.7/site-packages/iotop/data.py", line
> > > 196, in parse_proc_pid_status
> > >     key, value = line.split(':\t', 1)
> > > ValueError: need more than 1 value to unpack
> > >
> > > [reading /proc/self/status]
> > >
> > > Fixes: 84964fa3e5a0 ("proc: Provide details on speculation flaw mitigations")
> > >
> > > Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
> > > ---
> > >  v2: Format commit message properly with proper subject and fixes
> > >      keyword.
> > >
> > You might want to mention that this patch only applies to v4.4.y.
> > v4.9.y has a similar problem, but only if CONFIG_SECCOMP=n, and would
> > require a slightly different patch to fix. Other releases are, as far
> > as I can see, not affected.
> >
> > Guenter
> >
> > >  fs/proc/array.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/fs/proc/array.c b/fs/proc/array.c
> > > index 0c142916a8c7d..f11df9ab4256e 100644
> > > --- a/fs/proc/array.c
> > > +++ b/fs/proc/array.c
> > > @@ -334,7 +334,7 @@ static inline void task_seccomp(struct seq_file *m, struct task_struct *p)
> > >  #ifdef CONFIG_SECCOMP
> > >         seq_printf(m, "Seccomp:\t%d\n", p->seccomp.mode);
> > >  #endif
> > > -       seq_printf(m, "\nSpeculation_Store_Bypass:\t");
> > > +       seq_printf(m, "Speculation_Store_Bypass:\t");
>
> Why isn't this issue showing up in all kernel releases, as this line is
> still the same in 5.0-rc2?
>
> What makes the 4.4.y and 4.9.y trees so special here?
>

v4.14 and later:

{
        seq_put_decimal_ull(m, "NoNewPrivs:\t", task_no_new_privs(p));
#ifdef CONFIG_SECCOMP
        seq_put_decimal_ull(m, "\nSeccomp:\t", p->seccomp.mode);
#endif
        seq_printf(m, "\nSpeculation_Store_Bypass:\t");

---
v4.9:

{
#ifdef CONFIG_SECCOMP
        seq_put_decimal_ull(m, "Seccomp:\t", p->seccomp.mode);
                                                                ^^^
#endif
        seq_printf(m, "\nSpeculation_Store_Bypass:\t");
                               ^^^

-> extra newline if CONFIG_SECCOMP=n

---
v4.4:

{
#ifdef CONFIG_SECCOMP
        seq_printf(m, "Seccomp:\t%d\n", p->seccomp.mode);
                                                      ^^^
#endif
        seq_printf(m, "\nSpeculation_Store_Bypass:\t");
                               ^^^

-> always extra newline

Guenter