kernel/printk/index.c: fix memory leak with using debugfs_lookup()

[PATCH] kernel/printk/index.c: fix memory leak with using debugfs_lookup()

Posted by Greg Kroah-Hartman 3 years, 2 months ago

When calling debugfs_lookup() the result must have dput() called on it,
otherwise the memory will leak over time.  To make things simpler, just
call debugfs_lookup_and_remove() instead which handles all of the logic
at once.

Cc: Chris Down <chris@chrisdown.name>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 kernel/printk/index.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/printk/index.c b/kernel/printk/index.c
index c85be186a783..a6b27526baaf 100644
--- a/kernel/printk/index.c
+++ b/kernel/printk/index.c
@@ -145,7 +145,7 @@ static void pi_create_file(struct module *mod)
 #ifdef CONFIG_MODULES
 static void pi_remove_file(struct module *mod)
 {
-	debugfs_remove(debugfs_lookup(pi_get_module_name(mod), dfs_index));
+	debugfs_lookup_and_remove(pi_get_module_name(mod), dfs_index);
 }
 
 static int pi_module_notify(struct notifier_block *nb, unsigned long op,
-- 
2.39.1

Re: [PATCH] kernel/printk/index.c: fix memory leak with using debugfs_lookup()

Posted by Petr Mladek 3 years, 2 months ago

On Thu 2023-02-02 16:14:11, Greg Kroah-Hartman wrote:
> When calling debugfs_lookup() the result must have dput() called on it,
> otherwise the memory will leak over time.  To make things simpler, just
> call debugfs_lookup_and_remove() instead which handles all of the logic
> at once.
> 
> Cc: Chris Down <chris@chrisdown.name>
> Cc: Petr Mladek <pmladek@suse.com>
> Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: John Ogness <john.ogness@linutronix.de>
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

JFYI, the patch has been committed into printk/linux.git, branch for-6.3.

Best Regards,
Petr

Re: [PATCH] kernel/printk/index.c: fix memory leak with using debugfs_lookup()

Posted by Greg Kroah-Hartman 3 years, 1 month ago

On Fri, Feb 03, 2023 at 11:16:17AM +0100, Petr Mladek wrote:
> On Thu 2023-02-02 16:14:11, Greg Kroah-Hartman wrote:
> > When calling debugfs_lookup() the result must have dput() called on it,
> > otherwise the memory will leak over time.  To make things simpler, just
> > call debugfs_lookup_and_remove() instead which handles all of the logic
> > at once.
> > 
> > Cc: Chris Down <chris@chrisdown.name>
> > Cc: Petr Mladek <pmladek@suse.com>
> > Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
> > Cc: Steven Rostedt <rostedt@goodmis.org>
> > Cc: John Ogness <john.ogness@linutronix.de>
> > Cc: linux-kernel@vger.kernel.org
> > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> 
> JFYI, the patch has been committed into printk/linux.git, branch for-6.3.

Wonderful, thank you!

greg k-h

Re: [PATCH] kernel/printk/index.c: fix memory leak with using debugfs_lookup()

Posted by Petr Mladek 3 years, 2 months ago

On Thu 2023-02-02 16:14:11, Greg Kroah-Hartman wrote:
> When calling debugfs_lookup() the result must have dput() called on it,
> otherwise the memory will leak over time.  To make things simpler, just
> call debugfs_lookup_and_remove() instead which handles all of the logic
> at once.
> 
> Cc: Chris Down <chris@chrisdown.name>
> Cc: Petr Mladek <pmladek@suse.com>
> Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: John Ogness <john.ogness@linutronix.de>
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Reviewed-by: Petr Mladek <pmladek@suse.com>

Best Regards,
Petr

Re: [PATCH] kernel/printk/index.c: fix memory leak with using debugfs_lookup()

Posted by John Ogness 3 years, 2 months ago

On 2023-02-02, Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:
> When calling debugfs_lookup() the result must have dput() called on it,
> otherwise the memory will leak over time.  To make things simpler, just
> call debugfs_lookup_and_remove() instead which handles all of the logic
> at once.
>
> Cc: Chris Down <chris@chrisdown.name>
> Cc: Petr Mladek <pmladek@suse.com>
> Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: John Ogness <john.ogness@linutronix.de>
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Reviewed-by: John Ogness <john.ogness@linutronix.de>

Re: [PATCH] kernel/printk/index.c: fix memory leak with using debugfs_lookup()

Posted by Sergey Senozhatsky 3 years, 2 months ago

On (23/02/02 16:14), Greg Kroah-Hartman wrote:
> 
> When calling debugfs_lookup() the result must have dput() called on it,
> otherwise the memory will leak over time.  To make things simpler, just
> call debugfs_lookup_and_remove() instead which handles all of the logic
> at once.
> 
> Cc: Chris Down <chris@chrisdown.name>
> Cc: Petr Mladek <pmladek@suse.com>
> Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: John Ogness <john.ogness@linutronix.de>
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>