Re: [PATCH v2 1/4] misc: fastrpc: Add NULL check to fastrpc_buf_free to prevent crash

[Jianping]

On 1/16/2026 10:49 PM, Greg KH wrote:
> On Thu, Jan 15, 2026 at 04:28:48PM +0800, Jianping Li wrote:
> > From: Ekansh Gupta <ekansh.gupta@xxxxxxxxxxxxxxxx>
> >
> > The fastrpc_buf_free function currently does not handle the case where
> > the input buffer pointer (buf) is NULL. This can lead to a null pointer
> > dereference, causing a crash or undefined behavior when the function
> > attempts to access members of the buf structure. Add a NULL check to
> > ensure safe handling of NULL pointers and prevent potential crashes.
>
> What caller passes in NULL here?  I did a quick look, and see where the
> callers check this properly if it could be NULL, otherwise it all looks
> sane to me.  What in-kernel user is causing a crash here?  Why not fix
> the caller up instead?
>
> thanks,
>
> greg k-h

It's a saftety coding: to eliminate NULL checks on the caller side, as 
we do in a lot of other kernel API.

And it was pointed out in the v1 patch discussion that this change was 
needed:
https://lore.kernel.org/all/c80c48a1-f1b6-4520-9d7c-3a83915c7717@xxxxxxxxxxxxxxxx/

Thanks,
Jianping.