linux-kernel - Re: [PATCH] proc: readdir race fix.

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Message-ID: <m1d5ab3tw9.fsf@ebiederm.dsl.xmission.com>
Date:	Mon, 04 Sep 2006 20:54:30 -0600
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc:	linux-kernel@...r.kernel.org, akpm@...l.org,
	saito.tadashi@...t.fujitsu.com, ak@...e.de, oleg@...sign.ru,
	jdelvare@...e.de
Subject: Re: [PATCH] proc: readdir race fix.

KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> writes:

> On Mon, 04 Sep 2006 17:13:10 -0600
> ebiederm@...ssion.com (Eric W. Biederman) wrote:
> Hi, Hit OOM-Killer, because of memory leak of task struct.
>
> patch is attached.
> -Kame
>
> task struct should be put always.

Good catch. I actually have a pending cleanup that works better if the
task struct is held across the filldir so the incremental patch should look like:

I also noticed a benign typo in TGID_OFFSET (1 subtract one that I shouldn't)

Complete patch in just a moment.

Eric

diff --git a/fs/proc/base.c b/fs/proc/base.c
index b7650b9..03f6680 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2186,7 +2186,7 @@ int proc_pid_readdir(struct file * filp,
        tgid = filp->f_pos - TGID_OFFSET;
        for (task = next_tgid(tgid);
             task;
-            task = next_tgid(tgid + 1)) {
+            put_task_struct(task), task = next_tgid(tgid + 1)) {
                int len;
                ino_t ino;
                tgid = task->pid;

-
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