linux-kernel - [PATCH] char: mwave: fix return type in ioctl

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Date:   Thu, 4 Aug 2022 10:06:38 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alan Cox <alan@...rguk.ukuu.org.uk>,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: [PATCH] char: mwave: fix return type in ioctl

This function is supposed to return zero for success or negative error
code on failure.  Unfortunately the "retval" is declared as unsigned int
and the function returns type long.  That means that on 64 bit systems
it will return positive values on error.

Fixes: 909d145f0dec ("mwave: ioctl BKL pushdown")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
---
The Fixes tag is sort of debatable.  "retval" should have always been
declared as an int.  But the BKL change is when the return type for
the ioctl changed from int to long, so it's when the bug started to
affect user space.

 drivers/char/mwave/mwavedd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/char/mwave/mwavedd.c b/drivers/char/mwave/mwavedd.c
index 11272d605ecd..5813517faf4d 100644
--- a/drivers/char/mwave/mwavedd.c
+++ b/drivers/char/mwave/mwavedd.c
@@ -123,7 +123,7 @@ static int mwave_close(struct inode *inode, struct file *file)
 static long mwave_ioctl(struct file *file, unsigned int iocmd,
 							unsigned long ioarg)
 {
-	unsigned int retval = 0;
+	int retval = 0;
 	pMWAVE_DEVICE_DATA pDrvData = &mwave_s_mdd;
 	void __user *arg = (void __user *)ioarg;
 
-- 
2.35.1