linux-kernel - [PATCH] proc: Document why writing to /proc/pid/mem is a security hazard.

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Date:	Fri,  4 Mar 2011 20:39:35 -0500
From:	Stephen Wilson <wilsons@...rt.ca>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Al Viro <viro@...iv.linux.org.uk>, linux-kernel@...r.kernel.org,
	Stephen Wilson <wilsons@...rt.ca>
Subject: [PATCH] proc: Document why writing to /proc/pid/mem is a security hazard.


Signed-off-by: Stephen Wilson <wilsons@...rt.ca>
---
 fs/proc/base.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 9d096e8..9d55b7b 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -832,7 +832,11 @@ out_no_task:
 #define mem_write NULL
 
 #ifndef mem_write
-/* This is a security hazard */
+/*
+ * As implemented, mem_write would be a security hazard if enabled.  For
+ * example, the target task could exec a setuid-root binary between the
+ * permission check and the write into memory.
+ */
 static ssize_t mem_write(struct file * file, const char __user *buf,
 			 size_t count, loff_t *ppos)
 {
-- 
1.7.3.5

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