Re: [PATCH] ns83820: Avoid bad pointer deref in ns83820_init_one().
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From: Denis Kirjanov <dkirjanov@kernel.org>
Date: 2011-01-18 14:11:51
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On Mon, Jan 17, 2011 at 09:24:57PM +0100, Jesper Juhl wrote:
In drivers/net/ns83820.c::ns83820_init_one() we dynamically allocate memory via alloc_etherdev(). We then call PRIV() on the returned storage which is 'return netdev_priv()'. netdev_priv() takes the pointer it is passed and adds 'ALIGN(sizeof(struct net_device), NETDEV_ALIGN)' to it and returns it. Then we test the resulting pointer for NULL, which it is unlikely to be at this point, and later dereference it. This will go bad if alloc_etherdev() actually returned NULL. This patch reworks the code slightly so that we test for a NULL pointer (and return -ENOMEM) directly after calling alloc_etherdev(). Signed-off-by: Jesper Juhl <redacted>
Yeah, the previous code was a little bit ugly. Good catch!
quoted hunk ↗ jump to hunk
--- ns83820.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) Compile tested only. I have no way to test this for real.diff --git a/drivers/net/ns83820.c b/drivers/net/ns83820.c index 84134c7..a41b2cf 100644 --- a/drivers/net/ns83820.c +++ b/drivers/net/ns83820.c@@ -1988,12 +1988,11 @@ static int __devinit ns83820_init_one(struct pci_dev *pci_dev, } ndev = alloc_etherdev(sizeof(struct ns83820)); - dev = PRIV(ndev); - err = -ENOMEM; - if (!dev) + if (!ndev) goto out; + dev = PRIV(ndev); dev->ndev = ndev; spin_lock_init(&dev->rx_info.lock);-- Jesper Juhl <jj@chaosbits.net> http://www.chaosbits.net/ Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html Plain text mails only, please.