linux-kernel - [PATCH, 3.18-stable regression] gadgetfs: fix uninitialized variable in error handling

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Message-Id: <20170421130623.2668561-1-arnd@arndb.de>
Date:   Fri, 21 Apr 2017 15:06:12 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     stable@...r.kernel.org
Cc:     gregkh@...uxfoundation.org, Arnd Bergmann <arnd@...db.de>,
        Felipe Balbi <balbi@...com>, Bin Liu <b-liu@...com>,
        Sasha Levin <sasha.levin@...cle.com>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH, 3.18-stable regression] gadgetfs: fix uninitialized variable in error handling

gcc warns about a bug in 3.18.y:

drivers/usb/gadget/legacy/inode.c:648:10: warning: 'value' may be used

This is caused by the backport of f01d35a15fa0416 from 4.0 to 3.18:
c81fc59be42c6e0 gadgetfs: use-after-free in ->aio_read()

The backported patch was buggy, but the mainline code was rewritten
in a larger patch directly following this one in a way that fixed the
bug.

For stable, we should need only a one-line change to make sure we
return an proper error code. It is very unlikely that anybody ever
ran into the out-of-memory case here in practice, but the compiler
is right in theory.

Fixes: c81fc59be42c ("gadgetfs: use-after-free in ->aio_read()")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/usb/gadget/legacy/inode.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/usb/gadget/legacy/inode.c b/drivers/usb/gadget/legacy/inode.c
index 54f964bbc79a..fe45311f243e 100644
--- a/drivers/usb/gadget/legacy/inode.c
+++ b/drivers/usb/gadget/legacy/inode.c
@@ -654,6 +654,7 @@ fail:
 				   GFP_KERNEL);
 		if (!priv->iv) {
 			kfree(priv);
+			value = -ENOMEM;
 			goto fail;
 		}
 	}
-- 
2.9.0