netdev - Re: [PATCH net-next] devlink: Use after free in devlink_health_reporter

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Date:   Wed, 23 Jan 2019 09:52:14 +0000
From:   Eran Ben Elisha <eranbe@...lanox.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>,
        Jiri Pirko <jiri@...lanox.com>
CC:     "David S. Miller" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "kernel-janitors@...r.kernel.org" <kernel-janitors@...r.kernel.org>
Subject: Re: [PATCH net-next] devlink: Use after free in
 devlink_health_reporter_destroy()



On 1/23/2019 11:44 AM, Dan Carpenter wrote:
> This calls kfree(reporter); before dereferencing reporter on the next
> line when it does mutex_unlock(&reporter->devlink->lock);
> 
> Fixes: 880ee82f0313 ("devlink: Add health reporter create/destroy functionality")
> Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>

Hi, thanks for the fix.
It is identical to one I posted yesterday.
https://patchwork.ozlabs.org/patch/1029358/

> ---
>   net/core/devlink.c | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/net/core/devlink.c b/net/core/devlink.c
> index 60248a53c0ad..deccce13285a 100644
> --- a/net/core/devlink.c
> +++ b/net/core/devlink.c
> @@ -4223,14 +4223,16 @@ EXPORT_SYMBOL_GPL(devlink_health_reporter_create);
>   void
>   devlink_health_reporter_destroy(struct devlink_health_reporter *reporter)
>   {
> -	mutex_lock(&reporter->devlink->lock);
> +	struct devlink *devlink = reporter->devlink;
> +
> +	mutex_lock(&devlink->lock);
>   	list_del(&reporter->list);
>   	devlink_health_buffers_destroy(reporter->dump_buffers_array,
>   				       DEVLINK_HEALTH_SIZE_TO_BUFFERS(reporter->ops->dump_size));
>   	devlink_health_buffers_destroy(reporter->diagnose_buffers_array,
>   				       DEVLINK_HEALTH_SIZE_TO_BUFFERS(reporter->ops->diagnose_size));
>   	kfree(reporter);
> -	mutex_unlock(&reporter->devlink->lock);
> +	mutex_unlock(&devlink->lock);
>   }
>   EXPORT_SYMBOL_GPL(devlink_health_reporter_destroy);
>   
>