linux-kernel - [PATCH] kernel: Return -EFAULT if copy_to

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Date:   Mon,  1 Mar 2021 19:28:11 +0800
From:   Wang Qing <wangqing@...o.com>
To:     Christian Brauner <christian.brauner@...ntu.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Thomas Cedeno <thomascedeno@...gle.com>,
        Nicolas Viennot <Nicolas.Viennot@...sigma.com>,
        Michel Lespinasse <walken@...gle.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Al Viro <viro@...iv.linux.org.uk>,
        Gabriel Krisman Bertazi <krisman@...labora.com>,
        linux-kernel@...r.kernel.org
Cc:     Wang Qing <wangqing@...o.com>
Subject: [PATCH] kernel: Return -EFAULT if copy_to_user() fails

The copy_to_user() function returns the number of bytes remaining to be
copied, but we want to return -EFAULT if the copy doesn't complete.

Signed-off-by: Wang Qing <wangqing@...o.com>
---
 kernel/sys.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sys.c b/kernel/sys.c
index 8bb46e5..d97a84a
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1247,7 +1247,7 @@ static int override_release(char __user *release, size_t len)
 		copy = scnprintf(buf, copy, "2.6.%u%s", v, rest);
 		ret = copy_to_user(release, buf, copy + 1);
 	}
-	return ret;
+	return ret ? -EFAULT : 0;
 }
 
 SYSCALL_DEFINE1(newuname, struct new_utsname __user *, name)
-- 
2.7.4