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From: Dan Carpenter <error27@gmail.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Andrzej Pietrasiewicz <andrzej.p@collabora.com>
Cc: Dan Carpenter <error27@gmail.com>,
	Albert Briscoe <albertsbriscoe@gmail.com>,
	Zqiang <qiang.zhang@windriver.com>,
	Felipe Balbi <balbi@kernel.org>,
	linux-usb@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: [PATCH] usb: gadget: function: use after free in printer_close()
Date: Mon, 21 Nov 2022 17:44:21 +0300	[thread overview]
Message-ID: <Y3uOxcvowFq75Tzv@kili> (raw)

The printer_dev_free() function frees "dev" but then it is dereferenced
by the debug code on the next line.  Flip the order to avoid the use after
free.

Fixes: e8d5f92b8d30 ("usb: gadget: function: printer: fix use-after-free in __lock_acquire")
Signed-off-by: Dan Carpenter <error27@gmail.com>
---
v2: In the v1, I just deleted the printk but Andrzej thought it was
worth preserving.

 drivers/usb/gadget/function/f_printer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/gadget/function/f_printer.c b/drivers/usb/gadget/function/f_printer.c
index a881c69b1f2b..01e842e1ba2f 100644
--- a/drivers/usb/gadget/function/f_printer.c
+++ b/drivers/usb/gadget/function/f_printer.c
@@ -381,8 +381,8 @@ printer_close(struct inode *inode, struct file *fd)
 	dev->printer_status &= ~PRINTER_SELECTED;
 	spin_unlock_irqrestore(&dev->lock, flags);
 
-	kref_put(&dev->kref, printer_dev_free);
 	DBG(dev, "printer_close\n");
+	kref_put(&dev->kref, printer_dev_free);
 
 	return 0;
 }
-- 
2.35.1


             reply	other threads:[~2022-11-21 14:55 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-21 14:44 Dan Carpenter [this message]
2022-11-21 15:32 ` [PATCH] usb: gadget: function: use after free in printer_close() Andrzej Pietrasiewicz
2022-11-22  7:00   ` Dan Carpenter
2022-11-22  9:49     ` Andrzej Pietrasiewicz
2022-11-22 14:16       ` [PATCH] usb: gadget: function: Simplify error messaging in printer open/close Andrzej Pietrasiewicz
2022-11-22 15:54         ` Greg Kroah-Hartman
2022-11-23 11:07           ` [PATCH] usb: gadget: function: Simplify diagnostic messaging in printer Andrzej Pietrasiewicz
  -- strict thread matches above, loose matches on Subject: below --
2022-11-18 11:47 [PATCH] usb: gadget: function: use after free in printer_close() Dan Carpenter
2022-11-21 12:37 ` Andrzej Pietrasiewicz

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