Subject: Re: [PATCH] usbnet: smsc95xx: dereferencing NULL pointer

From: Sudip Mukherjee <[email-masked]>
Date: Tue, 11 Nov 2014 12:00:08 +0530

On Mon, Nov 10, 2014 at 02:22:23PM -0500, David Miller wrote:
> From: Sudip Mukherjee <[email-masked]>
> Date: Fri,  7 Nov 2014 18:52:40 +0530
> 
> > we were dereferencing dev to initialize pdata. but just after that we
> > have a BUG_ON(!dev). so we were basically dereferencing the pointer
> > first and then tesing it for NULL.
> > 
> > Signed-off-by: Sudip Mukherjee <[email-masked]>
> 
> You didn't even compile test this.
> 
> Do not even bother fixing theoretical issues if you're going to be
> introducing a _REAL_ serious regression into the code with your "fix":
> 
> drivers/net/usb/smsc95xx.c: In function ‘smsc95xx_resume’:
> drivers/net/usb/smsc95xx.c:1674:5: warning: ‘pdata’ is used uninitialized in this function [-Wuninitialized]
>   u8 suspend_flags = pdata->suspend_flags;
>      ^
> 
> So, instead of a theoretical issue, we now have a real guaranteed
> crash.
> 
> You did not compile test this change, and you definitely did not
> functionally test this change either.
> 
> Please do not do this ever again, thanks.

extremely sorry for this.
i have compile tested but don't know how i missed the new warning message.
for any of my patch,if for some reason i am not able to compile test it, i mention that in the comments.
sorry again.

thanks
sudip