linux-kernel - [PATCH 4.14 127/183] parport_pc: fix find_superio io compare code, should use equal test.

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Date:   Fri, 22 Mar 2019 12:15:55 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Alan Cox <alan@...ux.intel.com>,
        QiaoChong <qiaochong@...ngson.cn>,
        Sudip Mukherjee <sudipm.mukherjee@...il.com>
Subject: [PATCH 4.14 127/183] parport_pc: fix find_superio io compare code, should use equal test.

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: QiaoChong <qiaochong@...ngson.cn>

commit 21698fd57984cd28207d841dbdaa026d6061bceb upstream.

In the original code before 181bf1e815a2 the loop was continuing until
it finds the first matching superios[i].io and p->base.
But after 181bf1e815a2 the logic changed and the loop now returns the
pointer to the first mismatched array element which is then used in
get_superio_dma() and get_superio_irq() and thus returning the wrong
value.
Fix the condition so that it now returns the correct pointer.

Fixes: 181bf1e815a2 ("parport_pc: clean up the modified while loops using for")
Cc: Alan Cox <alan@...ux.intel.com>
Cc: stable@...r.kernel.org
Signed-off-by: QiaoChong <qiaochong@...ngson.cn>
[rewrite the commit message]
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@...il.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/parport/parport_pc.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/parport/parport_pc.c
+++ b/drivers/parport/parport_pc.c
@@ -1377,7 +1377,7 @@ static struct superio_struct *find_super
 {
 	int i;
 	for (i = 0; i < NR_SUPERIOS; i++)
-		if (superios[i].io != p->base)
+		if (superios[i].io == p->base)
 			return &superios[i];
 	return NULL;
 }