linux-kernel - [PATCH 3.16 09/10] timer/debug: Change /proc/timer

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Message-ID: <lsq.1557410897.804323871@decadent.org.uk>
Date:   Thu, 09 May 2019 15:08:17 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>
Subject: [PATCH 3.16 09/10] timer/debug: Change /proc/timer_stats from
 0644 to 0600

3.16.67-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Ben Hutchings <ben@...adent.org.uk>

The timer_stats facility should filter and translate PIDs if opened
from a non-initial PID namespace, to avoid leaking information about
the wider system.  It should also not show kernel virtual addresses.
Unfortunately it has now been removed upstream (as redundant)
instead of being fixed.

For stable, fix the leak by restricting access to root only.  A
similar change was already made for the /proc/timer_list file.

Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
--- a/kernel/time/timer_stats.c
+++ b/kernel/time/timer_stats.c
@@ -417,7 +417,7 @@ static int __init init_tstats_procfs(voi
 {
 	struct proc_dir_entry *pe;

-	pe = proc_create("timer_stats", 0644, NULL, &tstats_fops);
+	pe = proc_create("timer_stats", 0600, NULL, &tstats_fops);
 	if (!pe)
 		return -ENOMEM;
 	return 0;