linux-kernel - Re: [PATCH next] Drivers: hv: mshv: Prevent potential NULL dereference

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Message-ID: <Z92u-g59fWeMgwoJ@liuwe-devbox-ubuntu-v2.lamzopl0uupeniq2etz1fddiyg.xx.internal.cloudapp.net>
Date: Fri, 21 Mar 2025 18:24:58 +0000
From: Wei Liu <wei.liu@...nel.org>
To: Nuno Das Neves <nunodasneves@...ux.microsoft.com>
Cc: Dan Carpenter <dan.carpenter@...aro.org>,
	"wei.liu@...nel.org" <wei.liu@...nel.org>,
	"K. Y. Srinivasan" <kys@...rosoft.com>,
	Haiyang Zhang <haiyangz@...rosoft.com>,
	Dexuan Cui <decui@...rosoft.com>,
	Anirudh Rayabharam <anrayabh@...ux.microsoft.com>,
	Praveen K Paladugu <prapal@...ux.microsoft.com>,
	Stanislav Kinsburskii <skinsburskii@...ux.microsoft.com>,
	linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: Re: [PATCH next] Drivers: hv: mshv: Prevent potential NULL
 dereference

On Fri, Mar 21, 2025 at 09:53:45AM -0700, Nuno Das Neves wrote:
> On 3/21/2025 7:35 AM, Dan Carpenter wrote:
> > Move the NULL check on "partition" before the dereference.
> > 
> > Fixes: f5288d14069b ("Drivers: hv: Introduce mshv_root module to expose /dev/mshv to VMMs")
> > Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
> > ---
> >  drivers/hv/mshv_synic.c | 3 +--
> >  1 file changed, 1 insertion(+), 2 deletions(-)
> > 
> > diff --git a/drivers/hv/mshv_synic.c b/drivers/hv/mshv_synic.c
> > index a3daedd680ff..88949beb5e37 100644
> > --- a/drivers/hv/mshv_synic.c
> > +++ b/drivers/hv/mshv_synic.c
> > @@ -151,13 +151,12 @@ static bool mshv_async_call_completion_isr(struct hv_message *msg)
> >  	rcu_read_lock();
> >  
> >  	partition = mshv_partition_find(partition_id);
> > -	partition->async_hypercall_status = async_msg->status;
> > -
> >  	if (unlikely(!partition)) {
> >  		pr_debug("failed to find partition %llu\n", partition_id);
> >  		goto unlock_out;
> >  	}
> >  
> > +	partition->async_hypercall_status = async_msg->status;
> >  	complete(&partition->async_hypercall);
> >  
> >  	handled = true;
> 
> Thanks for catching this one!
> Wei could you please apply or squash this into the driver patch?

Thank you Dan. I squashed this fix to the original patch.