[PATCH] net/ieee802154/6lowpan: Fix initialization for fragment offset

[PATCH] net/ieee802154/6lowpan: Fix initialization for fragment offset

[Wolf-Bastian Pöttner]

offset has to be initialized, otherwise the *first* fragment will
be discarded and reassembly cannot happen.

Reviewed-by: Alan Ott <alan-yzvJWuRpmD1zbRFIqnYvSA@public.gmane.org>
---
 net/ieee802154/6lowpan.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/net/ieee802154/6lowpan.c b/net/ieee802154/6lowpan.c
index ed3debe..2db7261 100644
--- a/net/ieee802154/6lowpan.c
+++ b/net/ieee802154/6lowpan.c
@@ -745,7 +745,7 @@ lowpan_process_data(struct sk_buff *skb)
 	{
 		struct lowpan_fragment *frame;
 		/* slen stores the rightmost 8 bits of the 11 bits length */
-		u8 slen, offset;
+		u8 slen, offset = 0;
 		u16 len, tag;
 		bool found = false;
 
-- 
1.7.5.4


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Re: [PATCH] net/ieee802154/6lowpan: Fix initialization for fragment offset

[David Miller]

From: Wolf-Bastian Pöttner <poettner@ibr.cs.tu-bs.de>
Date: Wed, 13 Mar 2013 08:50:54 +0100

> offset has to be initialized, otherwise the *first* fragment will
> be discarded and reassembly cannot happen.
> 
> Reviewed-by: Alan Ott <alan@signal11.us>

'offset' is never used unless lowpan_fetch_skb_u8(skb, &offset)
succeeds, in which case it will be initialized properly.  Otherwise we
unlock and drop the SKB and make no references whatsoever to 'offset'.

I suspect you saw some compiler warning about 'offset' being
uninitialized, and are just blindly trying to shut this warning up.

Re: [PATCH] net/ieee802154/6lowpan: Fix initialization for fragment offset

[Wolf-Bastian Pöttner]

Hi!


Nope. The patch fixes a problem in code that is not in mainline yet. However, people on the linux-zigbee mailing list found it a good idea to commit this change to mainline to avoid the problem from arising.

I see, you disagree. Nevermind. ;)


Bastian
-- 
Wolf-Bastian Pöttner      Institut für Betriebssysteme & Rechnerverbund
Tel.: +49-531-391-3265                           Mühlenpfordtstrasse 23
Fax.: +49-531-391-5936         TU Braunschweig     D-38106 Braunschweig

Am 13.03.2013 um 15:38 schrieb David Miller <davem@davemloft.net>:

> From: Wolf-Bastian Pöttner <poettner@ibr.cs.tu-bs.de>
> Date: Wed, 13 Mar 2013 08:50:54 +0100
> 
>> offset has to be initialized, otherwise the *first* fragment will
>> be discarded and reassembly cannot happen.
>> 
>> Reviewed-by: Alan Ott <alan@signal11.us>
> 
> 'offset' is never used unless lowpan_fetch_skb_u8(skb, &offset)
> succeeds, in which case it will be initialized properly.  Otherwise we
> unlock and drop the SKB and make no references whatsoever to 'offset'.
> 
> I suspect you saw some compiler warning about 'offset' being
> uninitialized, and are just blindly trying to shut this warning up.

Re: [PATCH] net/ieee802154/6lowpan: Fix initialization for fragment offset

[Alan Ott]

[-- Attachment #1.1: Type: text/plain, Size: 1280 bytes --]

On 03/13/2013 10:40 AM, Wolf-Bastian Pöttner wrote:
> Nope. The patch fixes a problem in code that is not in mainline yet. However, people on the linux-zigbee mailing list found it a good idea to commit this change to mainline to avoid the problem from arising.
>
> I see, you disagree. Nevermind. ;)

Hi David,

This is my fault. I must have been looking the wrong tree when I
recommended a push to mainline.

Sorry for the noise.

Alan.

> Am 13.03.2013 um 15:38 schrieb David Miller <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>:
>> > From: Wolf-Bastian Pöttner <poettner-G+tS6SCNB47quOJu9mQKZg@public.gmane.org>
>> > Date: Wed, 13 Mar 2013 08:50:54 +0100
>> > 
>>> >> offset has to be initialized, otherwise the *first* fragment will
>>> >> be discarded and reassembly cannot happen.
>>> >> 
>>> >> Reviewed-by: Alan Ott <alan-yzvJWuRpmD1zbRFIqnYvSA@public.gmane.org>
>> > 
>> > 'offset' is never used unless lowpan_fetch_skb_u8(skb, &offset)
>> > succeeds, in which case it will be initialized properly.  Otherwise we
>> > unlock and drop the SKB and make no references whatsoever to 'offset'.
>> > 
>> > I suspect you saw some compiler warning about 'offset' being
>> > uninitialized, and are just blindly trying to shut this warning up.
>


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