linux-kernel - Re: [TIP] BUG kmalloc-4096: Poison overwritten (ath5k_rx_skb

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Message-Id: <20090226205921.M20262@bobcopeland.com>
Date:	Thu, 26 Feb 2009 16:05:06 -0500
From:	"Bob Copeland" <me@...copeland.com>
To:	Jiri Slaby <jirislaby@...il.com>
Cc:	Sitsofe Wheeler <sitsofe@...oo.com>,
	Nick Kossifidis <mickflemm@...il.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	linux-kernel@...r.kernel.org, linux-wireless@...r.kernel.org,
	ath5k-devel@...ema.h4ckr.net,
	"Luis R. Rodriguez" <lrodriguez@...eros.com>
Subject: Re: [TIP] BUG kmalloc-4096: Poison overwritten (ath5k_rx_skb_alloc)

On Thu, 26 Feb 2009 21:53:08 +0100, Jiri Slaby wrote
> On 26.2.2009 02:06, Bob Copeland wrote:
> > --- a/drivers/net/wireless/ath5k/base.c
> > +++ b/drivers/net/wireless/ath5k/base.c
> > @@ -1140,12 +1140,14 @@ ath5k_rxbuf_setup(struct ath5k_softc *sc, struct
ath5k_buf *bf)
> >   	struct ath5k_hw *ah = sc->ah;
> >   	struct sk_buff *skb = bf->skb;
> >   	struct ath5k_desc *ds;
> > +	dma_addr_t dma_addr;
> >
> >   	if (!skb) {
> > -		skb = ath5k_rx_skb_alloc(sc,&bf->skbaddr);
> > +		skb = ath5k_rx_skb_alloc(sc,&dma_addr);
> >   		if (!skb)
> >   			return -ENOMEM;
> >   		bf->skb = skb;
> > +		bf->skbaddr = dma_addr;
> 
> Hmm, rather than the caller, ath5k_rx_skb_alloc is wrong here in my 
> eyes. It shouldn't touch the second parameter unless it knows it won't 
> fail anymore.

Sure, the temporary could go there instead.  It's a consequence of my
making ath5k_rx_skb_alloc() as much as possible a straight code move
from the original, which IIRC would also clobber bf->skbaddr on the
error path.

-- 
Bob Copeland %% www.bobcopeland.com


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