[PATCH v2] init: Do not warn on non-zero initcall return

[PATCH v2] init: Do not warn on non-zero initcall return

[Steven Rostedt]

Commit f91eb62f71 "init: scream bloody murder if interrupts are enabled
too early" added three new warnings. The first two seemed reasonable,
but the third included a warning when an initcall returned non-zero.
Although, the third WARN() does include an imbalanced preempt disabled,
or irqs disable, it shouldn't warn if it only had an initcall that just
returns non-zero.

In fact, according to Linus, it shouldn't print at all. As it only
prints with initcall_debug set, and that already shows enough
information to fix things.

Link: http://lkml.kernel.org/r/CA+55aFzaBC5SFi7=F2mfm+KWY5qTsBmOqgbbs8E+LUS8JK-sBg@mail.gmail.com

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/init/main.c b/init/main.c
index bea1287..ceed17a 100644
--- a/init/main.c
+++ b/init/main.c
@@ -686,11 +686,8 @@ int __init_or_module do_one_initcall(initcall_t fn)
 
 	msgbuf[0] = 0;
 
-	if (ret && ret != -ENODEV && initcall_debug)
-		sprintf(msgbuf, "error code %d ", ret);
-
 	if (preempt_count() != count) {
-		strlcat(msgbuf, "preemption imbalance ", sizeof(msgbuf));
+		sprintf(msgbuf, "preemption imbalance ");
 		preempt_count() = count;
 	}
 	if (irqs_disabled()) {

Re: [PATCH v2] init: Do not warn on non-zero initcall return

[Geert Uytterhoeven]

On Wed, May 1, 2013 at 7:35 PM, Steven Rostedt <rostedt@goodmis.org> wrote:
> Commit f91eb62f71 "init: scream bloody murder if interrupts are enabled
> too early" added three new warnings. The first two seemed reasonable,
> but the third included a warning when an initcall returned non-zero.
> Although, the third WARN() does include an imbalanced preempt disabled,
> or irqs disable, it shouldn't warn if it only had an initcall that just
> returns non-zero.
>
> In fact, according to Linus, it shouldn't print at all. As it only
> prints with initcall_debug set, and that already shows enough
> information to fix things.
>
> Link: http://lkml.kernel.org/r/CA+55aFzaBC5SFi7=F2mfm+KWY5qTsBmOqgbbs8E+LUS8JK-sBg@mail.gmail.com
>
> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
> Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
>
> diff --git a/init/main.c b/init/main.c
> index bea1287..ceed17a 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -686,11 +686,8 @@ int __init_or_module do_one_initcall(initcall_t fn)
>
>         msgbuf[0] = 0;
>
> -       if (ret && ret != -ENODEV && initcall_debug)
> -               sprintf(msgbuf, "error code %d ", ret);
> -
>         if (preempt_count() != count) {
> -               strlcat(msgbuf, "preemption imbalance ", sizeof(msgbuf));
> +               sprintf(msgbuf, "preemption imbalance ");

snprintf(), please?

JFYI, the v3.9 version already used up all of msgbuf[] in the
worst-case scenario,
and it did have the strlcat() as a parachute:

$ echo -n "error code 1234567890 preemption imbalance disabled
interrupts " | wc -c
63
$

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH v2] init: Do not warn on non-zero initcall return

[Steven Rostedt]

On Thu, 2013-05-02 at 09:43 +0200, Geert Uytterhoeven wrote:
> On Wed, May 1, 2013 at 7:35 PM, Steven Rostedt <rostedt@goodmis.org> wrote:
> > Commit f91eb62f71 "init: scream bloody murder if interrupts are enabled
> > too early" added three new warnings. The first two seemed reasonable,
> > but the third included a warning when an initcall returned non-zero.
> > Although, the third WARN() does include an imbalanced preempt disabled,
> > or irqs disable, it shouldn't warn if it only had an initcall that just
> > returns non-zero.
> >
> > In fact, according to Linus, it shouldn't print at all. As it only
> > prints with initcall_debug set, and that already shows enough
> > information to fix things.
> >
> > Link: http://lkml.kernel.org/r/CA+55aFzaBC5SFi7=F2mfm+KWY5qTsBmOqgbbs8E+LUS8JK-sBg@mail.gmail.com
> >
> > Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
> > Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> > Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> >
> > diff --git a/init/main.c b/init/main.c
> > index bea1287..ceed17a 100644
> > --- a/init/main.c
> > +++ b/init/main.c
> > @@ -686,11 +686,8 @@ int __init_or_module do_one_initcall(initcall_t fn)
> >
> >         msgbuf[0] = 0;
> >
> > -       if (ret && ret != -ENODEV && initcall_debug)
> > -               sprintf(msgbuf, "error code %d ", ret);
> > -
> >         if (preempt_count() != count) {
> > -               strlcat(msgbuf, "preemption imbalance ", sizeof(msgbuf));
> > +               sprintf(msgbuf, "preemption imbalance ");
> 
> snprintf(), please?

Why? The msgbuf is 64 bytes, this is the first occurrence and
"preemption imbalance " is much less than 64 bytes.

> 
> JFYI, the v3.9 version already used up all of msgbuf[] in the
> worst-case scenario,
> and it did have the strlcat() as a parachute:

Right, the other users had strlcat as they were not the first user and
add onto the string.

-- Steve

> 
> $ echo -n "error code 1234567890 preemption imbalance disabled
> interrupts " | wc -c
> 63
> $

Re: [PATCH v2] init: Do not warn on non-zero initcall return

[Geert Uytterhoeven]

On Thu, May 2, 2013 at 5:17 PM, Steven Rostedt <rostedt@goodmis.org> wrote:
> On Thu, 2013-05-02 at 09:43 +0200, Geert Uytterhoeven wrote:
>> On Wed, May 1, 2013 at 7:35 PM, Steven Rostedt <rostedt@goodmis.org> wrote:
>> > --- a/init/main.c
>> > +++ b/init/main.c
>> > @@ -686,11 +686,8 @@ int __init_or_module do_one_initcall(initcall_t fn)
>> >
>> >         msgbuf[0] = 0;
>> >
>> > -       if (ret && ret != -ENODEV && initcall_debug)
>> > -               sprintf(msgbuf, "error code %d ", ret);
>> > -
>> >         if (preempt_count() != count) {
>> > -               strlcat(msgbuf, "preemption imbalance ", sizeof(msgbuf));
>> > +               sprintf(msgbuf, "preemption imbalance ");
>>
>> snprintf(), please?
>
> Why? The msgbuf is 64 bytes, this is the first occurrence and
> "preemption imbalance " is much less than 64 bytes.

The day after tomorrow, someone will modify the code, and cause a buffer
overflow.

I'm actually surprised (v)sprintf() is not tagged __deprecated.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH v2] init: Do not warn on non-zero initcall return

[Steven Rostedt]

On Thu, 2013-05-02 at 20:33 +0200, Geert Uytterhoeven wrote:
> On Thu, May 2, 2013 at 5:17 PM, Steven Rostedt <rostedt@goodmis.org> wrote:
> > On Thu, 2013-05-02 at 09:43 +0200, Geert Uytterhoeven wrote:
> >> On Wed, May 1, 2013 at 7:35 PM, Steven Rostedt <rostedt@goodmis.org> wrote:
> >> > --- a/init/main.c
> >> > +++ b/init/main.c
> >> > @@ -686,11 +686,8 @@ int __init_or_module do_one_initcall(initcall_t fn)
> >> >
> >> >         msgbuf[0] = 0;
> >> >
> >> > -       if (ret && ret != -ENODEV && initcall_debug)
> >> > -               sprintf(msgbuf, "error code %d ", ret);
> >> > -
> >> >         if (preempt_count() != count) {
> >> > -               strlcat(msgbuf, "preemption imbalance ", sizeof(msgbuf));
> >> > +               sprintf(msgbuf, "preemption imbalance ");
> >>
> >> snprintf(), please?
> >
> > Why? The msgbuf is 64 bytes, this is the first occurrence and
> > "preemption imbalance " is much less than 64 bytes.
> 
> The day after tomorrow, someone will modify the code, and cause a buffer
> overflow.
> 
> I'm actually surprised (v)sprintf() is not tagged __deprecated.
> 

I actually did think for a second in adding that. Not sure why I didn't.
Probably just because the original code didn't do that.

But I'll let that clean up come another day by someone else.

-- Steve