Messages in this thread Patch in this message | | | Date | Sun, 29 Jul 2007 23:48:24 +0530 (IST) | From | Satyam Sharma <> | Subject | Re: [linux-usb-devel] [PATCH] USB Pegasus driver - avoid a potential NULL pointer dereference. |
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On Sun, 29 Jul 2007, Oliver Neukum wrote:
> Am Sonntag 29 Juli 2007 schrieb Jesper Juhl: > > On 29/07/07, Satyam Sharma <satyam.sharma@gmail.com> wrote: > > > Hi, > > > > > > On 7/29/07, Jesper Juhl <jesper.juhl@gmail.com> wrote: > > > > Hello, > > > > > > > > This patch makes sure we don't dereference a NULL pointer in > > > > drivers/net/usb/pegasus.c::write_bulk_callback() in the initial > > > > struct net_device *net = pegasus->net; assignment. > > > > The existing code checks if 'pegasus' is NULL and bails out if > > > > it is, so we better not touch that pointer until after that check. > > > > [...] > > > > > > Is it really possible that we're called into this function with > > > urb->context == NULL? If not, I'd suggest let's just get rid of > > > the check itself, instead. > > > > > I'm not sure. I am not very familiar with this code. I just figured > > that moving the assignment is potentially a little safer and it is > > certainly no worse than the current code, so that's a safe and > > potentially benneficial change. Removing the check may be safe but I'm > > not certain enough to make that call... > > pegasus == NULL there would be a kernel bug. Silently ignoring > it, like the code now wants to do is bad. As the oops has never been > reported, I figure turning it into an explicit debugging test is overkill, > so removal seems to be the best option.
Ok, thanks. Updated patch below.
[PATCH] pegasus: Remove bogus checks in urb->complete() callbacks
urb->complete() callbacks registered in drivers/net/usb/pegasus.c needlessly check for urb->context != NULL, but that is not possible (the only way that can be possible would be a kernel bug elsewhere, and these checks would simply end up hiding that). So let's remove the bogus checks.
Signed-off-by: Satyam Sharma <satyam@infradead.org>
---
drivers/net/usb/pegasus.c | 9 +-------- 1 files changed, 1 insertions(+), 8 deletions(-)
diff --git a/drivers/net/usb/pegasus.c b/drivers/net/usb/pegasus.c index a05fd97..439ef9f 100644 --- a/drivers/net/usb/pegasus.c +++ b/drivers/net/usb/pegasus.c @@ -770,9 +770,6 @@ static void write_bulk_callback(struct urb *urb) pegasus_t *pegasus = urb->context; struct net_device *net = pegasus->net; - if (!pegasus) - return; - if (!netif_device_present(net) || !netif_running(net)) return; @@ -805,13 +802,9 @@ static void write_bulk_callback(struct urb *urb) static void intr_callback(struct urb *urb) { pegasus_t *pegasus = urb->context; - struct net_device *net; + struct net_device *net = pegasus->net; int status; - if (!pegasus) - return; - net = pegasus->net; - switch (urb->status) { case 0: break; - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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