linux-kernel - [PATCH 4/4] b43legacy: fix debugfs crash

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Date:   Sat, 17 Sep 2016 21:43:04 +0200
From:   Christian Lamparter <chunkeey@...glemail.com>
To:     gregkh@...uxfoundation.org, Kalle Valo <kvalo@...eaurora.org>
Cc:     Christian Lamparter <chunkeey@...il.com>,
        linux-kernel@...r.kernel.org, linux-wireless@...r.kernel.org,
        b43-dev@...ts.infradead.org, Nicolai Stange <nicstange@...il.com>,
        Ben Greear <greearb@...delatech.com>,
        Larry Finger <Larry.Finger@...inger.net>
Subject: [PATCH 4/4] b43legacy: fix debugfs crash

This patch fixes a crash that happens because b43legacy's
debugfs code expects file->f_op to be a pointer to its own
b43legacy_debugfs_fops struct. This is no longer the case
since commit 9fd4dcece43a
("debugfs: prevent access to possibly dead file_operations at file open")

Reviewed-by: Nicolai Stange <nicstange@...il.com>
Signed-off-by: Christian Lamparter <chunkeey@...il.com>
---
 drivers/net/wireless/broadcom/b43legacy/debugfs.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/broadcom/b43legacy/debugfs.c b/drivers/net/wireless/broadcom/b43legacy/debugfs.c
index 090910e..82ef56e 100644
--- a/drivers/net/wireless/broadcom/b43legacy/debugfs.c
+++ b/drivers/net/wireless/broadcom/b43legacy/debugfs.c
@@ -221,7 +221,8 @@ static ssize_t b43legacy_debugfs_read(struct file *file, char __user *userbuf,
 		goto out_unlock;
 	}
 
-	dfops = container_of(file->f_op, struct b43legacy_debugfs_fops, fops);
+	dfops = container_of(debugfs_real_fops(file),
+			     struct b43legacy_debugfs_fops, fops);
 	if (!dfops->read) {
 		err = -ENOSYS;
 		goto out_unlock;
@@ -287,7 +288,8 @@ static ssize_t b43legacy_debugfs_write(struct file *file,
 		goto out_unlock;
 	}
 
-	dfops = container_of(file->f_op, struct b43legacy_debugfs_fops, fops);
+	dfops = container_of(debugfs_real_fops(file),
+			     struct b43legacy_debugfs_fops, fops);
 	if (!dfops->write) {
 		err = -ENOSYS;
 		goto out_unlock;
-- 
2.9.3