linux-kernel - [patch 2/2] gru: cleanup gru_dump

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Message-ID: <20140130121048.GA17321@elgon.mountain>
Date:	Thu, 30 Jan 2014 15:10:48 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Dimitri Sivanich <sivanich@....com>
Cc:	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: [patch 2/2] gru: cleanup gru_dump_context() a little

"ret" is zero here so we can remove the "!ret" part of the condition.
"uhdr" is alread a __user pointer so we can remove the cast.

Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
---
Btw, speaking of __user pointers there are some places where we
dereference them in this file.  It's not a security problem because we
have already used copy_to_user() to successfully write to the pointer at
point.  But if you have something like PAX which puts user pointers and
kernel pointers in a separate address space then this will cause
problems.

Run sparse to see the issue.

diff --git a/drivers/misc/sgi-gru/grukdump.c b/drivers/misc/sgi-gru/grukdump.c
index 2bef3f76032a..a3700a56b8ff 100644
--- a/drivers/misc/sgi-gru/grukdump.c
+++ b/drivers/misc/sgi-gru/grukdump.c
@@ -178,10 +178,10 @@ static int gru_dump_context(struct gru_state *gru, int ctxnum,
 	hdr.cbrcnt = cbrcnt;
 	hdr.dsrcnt = dsrcnt;
 	hdr.cch_locked = cch_locked;
-	if (!ret && copy_to_user((void __user *)uhdr, &hdr, sizeof(hdr)))
-		ret = -EFAULT;
+	if (copy_to_user(uhdr, &hdr, sizeof(hdr)))
+		return -EFAULT;
 
-	return ret ? ret : bytes;
+	return bytes;
 }
 
 int gru_dump_chiplet_request(unsigned long arg)
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