linux-kernel - Re: [PATCH v2 1/4] misc: fastrpc: Add NULL check to fastrpc_buf

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Message-ID: <2026011621-fang-moneywise-d6b2@gregkh>
Date: Fri, 16 Jan 2026 15:49:08 +0100
From: Greg KH <gregkh@...uxfoundation.org>
To: Jianping Li <jianping.li@....qualcomm.com>
Cc: srini@...nel.org, amahesh@....qualcomm.com, arnd@...db.de,
	linux-arm-msm@...r.kernel.org,
	Ekansh Gupta <ekansh.gupta@....qualcomm.com>,
	thierry.escande@...aro.org, abelvesa@...nel.org,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	quic_chennak@...cinc.com, stable@...nel.org
Subject: Re: [PATCH v2 1/4] misc: fastrpc: Add NULL check to fastrpc_buf_free
 to prevent crash

On Thu, Jan 15, 2026 at 04:28:48PM +0800, Jianping Li wrote:
> From: Ekansh Gupta <ekansh.gupta@....qualcomm.com>
> 
> 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