* Re: [PATCH] lockdep: Make print_lock() address visible
[not found] <20190917013946.9EC51C60479@www.outflux.net>
@ 2019-09-17 3:07 ` Kees Cook
2019-09-18 0:28 ` Paul E. McKenney
0 siblings, 1 reply; 2+ messages in thread
From: Kees Cook @ 2019-09-17 3:07 UTC (permalink / raw)
To: Paul E. McKenney; +Cc: linux-kernel
On Mon, Sep 16, 2019 at 06:39:46PM -0700, keescook@chromium.org wrote:
> commit 519248f36d6f3c80e176f6fa844c10d94f1f5990
> Author: Paul E. McKenney <paulmck@linux.ibm.com>
> Date: Thu May 30 05:39:25 2019 -0700
>
> lockdep: Make print_lock() address visible
>
> Security is a wonderful thing, but so is the ability to debug based on
> lockdep warnings. This commit therefore makes lockdep lock addresses
> visible in the clear.
>
> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
>
> diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
> index 4861cf8e274b..4aca3f4379d2 100644
> --- a/kernel/locking/lockdep.c
> +++ b/kernel/locking/lockdep.c
> @@ -620,7 +620,7 @@ static void print_lock(struct held_lock *hlock)
> return;
> }
>
> - printk(KERN_CONT "%p", hlock->instance);
> + printk(KERN_CONT "%px", hlock->instance);
> print_lock_name(lock);
> printk(KERN_CONT ", at: %pS\n", (void *)hlock->acquire_ip);
> }
Just to clarify: this is only visible under CONFIG_LOCKDEP, yes? That's
not a state anyone would run a production system under, I'd hope.
--
Kees Cook
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] lockdep: Make print_lock() address visible
2019-09-17 3:07 ` [PATCH] lockdep: Make print_lock() address visible Kees Cook
@ 2019-09-18 0:28 ` Paul E. McKenney
0 siblings, 0 replies; 2+ messages in thread
From: Paul E. McKenney @ 2019-09-18 0:28 UTC (permalink / raw)
To: Kees Cook; +Cc: Paul E. McKenney, linux-kernel
On Mon, Sep 16, 2019 at 08:07:55PM -0700, Kees Cook wrote:
> On Mon, Sep 16, 2019 at 06:39:46PM -0700, keescook@chromium.org wrote:
> > commit 519248f36d6f3c80e176f6fa844c10d94f1f5990
> > Author: Paul E. McKenney <paulmck@linux.ibm.com>
> > Date: Thu May 30 05:39:25 2019 -0700
> >
> > lockdep: Make print_lock() address visible
> >
> > Security is a wonderful thing, but so is the ability to debug based on
> > lockdep warnings. This commit therefore makes lockdep lock addresses
> > visible in the clear.
> >
> > Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
> >
> > diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
> > index 4861cf8e274b..4aca3f4379d2 100644
> > --- a/kernel/locking/lockdep.c
> > +++ b/kernel/locking/lockdep.c
> > @@ -620,7 +620,7 @@ static void print_lock(struct held_lock *hlock)
> > return;
> > }
> >
> > - printk(KERN_CONT "%p", hlock->instance);
> > + printk(KERN_CONT "%px", hlock->instance);
> > print_lock_name(lock);
> > printk(KERN_CONT ", at: %pS\n", (void *)hlock->acquire_ip);
> > }
>
> Just to clarify: this is only visible under CONFIG_LOCKDEP, yes? That's
> not a state anyone would run a production system under, I'd hope.
Yes, by my reading of kernel/locking/Makefile, the entire
kernel/locking/lockdep.c file is completely ignored unless
CONFIG_LOCKDEP=y.
So yes, it would be silly for this code to be in a production
system.
Thanx, Paul
^ permalink raw reply [flat|nested] 2+ messages in thread
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2019-09-17 3:07 ` [PATCH] lockdep: Make print_lock() address visible Kees Cook
2019-09-18 0:28 ` Paul E. McKenney
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