Re: [PATCH] drivers/net/can/sja1000/plx_pci.c: eliminate double free

[David Miller <davem@davemloft.net>]

From: Julia Lawall <julia@diku.dk>
Date: Mon,  8 Aug 2011 18:28:50 +0200

> From: Julia Lawall <julia@diku.dk>
> 
> In this code, the failure_cleanup label calls the function
> plx_pci_del_card, which frees everything in the card->net_dev array.  dev
> is placed in this array immediately after allocation, so the two subsequent
> jumps to failure_cleanup should not also call free_sja1000dev, but the
> second one does.
> 
> If plx_pci_check_sja1000 fails, then free_sja1000dev is also called on
> dev.  Because dev is already in the card->net_dev array, this implies that
> when plx_pci_del_card is later called, it may get freed again.  So that
> entry is reset to NULL after the free.
> 
> Finally, if there is a problem with one channel, there will be a hole in the
> array.  card->channels counts the number of channels that have succeeded,
> and does not keep track of the index of the largest element in the array
> that is valid.  So the loop in plx_pci_del_card is changed to go up to
> PLX_PCI_MAX_CHAN, which is only 2.
> 
> Signed-off-by: Julia Lawall <julia@diku.dk>

Applied.