linux-kernel - [PATH v4] itimers: Remove bogus NULL pointer check in sys

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Date:	Tue, 25 Jun 2013 09:16:31 +0800
From:	Chen Gang <gang.chen@...anux.com>
To:	Thomas Gleixner <tglx@...utronix.de>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [PATH v4] itimers: Remove bogus NULL pointer check in sys_getitimer()

People might be tricked into assuming that the return value for a
failed NULL pointer check should be -EINVAL instead of -EFAULT.

Remove the misleading NULL pointer check to fix this nuisance.

Aside of that this patch fixes the problem of NOMMU kernels, where
a NULL pointer dereference is a valid operation. This allows to
boot NOMMU kernels without working around the shortcomings of the
getitimer() system call, which have been ignored since this NULL
pointer check was introduced in Linux 0.96a.

Signed-off-by: Chen Gang <gang.chen@...anux.com>
---
 kernel/itimer.c |   13 ++++++-------
 1 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/kernel/itimer.c b/kernel/itimer.c
index 8d262b4..3b12271 100644
--- a/kernel/itimer.c
+++ b/kernel/itimer.c
@@ -102,15 +102,14 @@ int do_getitimer(int which, struct itimerval *value)
 
 SYSCALL_DEFINE2(getitimer, int, which, struct itimerval __user *, value)
 {
-	int error = -EFAULT;
+	int error;
 	struct itimerval get_buffer;
 
-	if (value) {
-		error = do_getitimer(which, &get_buffer);
-		if (!error &&
-		    copy_to_user(value, &get_buffer, sizeof(get_buffer)))
-			error = -EFAULT;
-	}
+	error = do_getitimer(which, &get_buffer);
+	if (!error &&
+	    copy_to_user(value, &get_buffer, sizeof(get_buffer)))
+		error = -EFAULT;
+
 	return error;
 }
 
-- 
1.7.7.6



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