From: Al Viro <viro@zeniv.linux.org.uk>
To: Yahu Gao <yahu.gao@windriver.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH] fs/proc: Fix NULL pointer dereference in pid_delete_dentry
Date: Wed, 9 Dec 2020 13:16:52 +0000 [thread overview]
Message-ID: <20201209131652.GM3579531@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20201209112100.47653-2-yahu.gao@windriver.com>
On Wed, Dec 09, 2020 at 07:21:00PM +0800, Yahu Gao wrote:
> Get the staus of task from the pointer of proc inode directly is not
> safe. The function get_proc_task make it happen in RCU protection.
This is completely broken, get_proc_task() acquires a reference to
task_struct; your patch is an instant leak.
> Signed-off-by: Yahu Gao <yahu.gao@windriver.com>
> ---
> fs/proc/base.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index 1bc9bcdef09f..05f33bb35067 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -1994,7 +1994,7 @@ static int pid_revalidate(struct dentry *dentry, unsigned int flags)
>
> static inline bool proc_inode_is_dead(struct inode *inode)
> {
> - return !proc_pid(inode)->tasks[PIDTYPE_PID].first;
> + return !get_proc_task(inode);
> }
>
> int pid_delete_dentry(const struct dentry *dentry)
> --
> 2.25.1
>
next prev parent reply other threads:[~2020-12-09 13:17 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-09 11:20 Review request 0/1: fs/proc: Fix NULL pointer dereference in Yahu Gao
2020-12-09 11:21 ` [PATCH] fs/proc: Fix NULL pointer dereference in pid_delete_dentry Yahu Gao
2020-12-09 13:16 ` Al Viro [this message]
2021-01-07 9:41 ` [PATCH v2] " Gao Yahu
2020-12-09 21:54 ` Review request 0/1: fs/proc: Fix NULL pointer dereference in Eric W. Biederman
2021-01-07 9:02 ` Gao Yahu
2021-01-07 9:03 ` Gao, Yahu
2021-01-07 9:07 ` Gao Yahu
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