netdev - RE: [PATCH net] net/smc: fix one NULL pointer dereference in smc_ib_is_sg_need

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Message-ID: <9ae4d764df69431cb77f5c5c32eaa911@huawei.com>
Date: Wed, 27 Aug 2025 10:48:39 +0000
From: "liujian (CE)" <liujian56@...wei.com>
To: "D. Wythe" <alibuda@...ux.alibaba.com>
CC: "dust.li@...ux.alibaba.com" <dust.li@...ux.alibaba.com>,
	"sidraya@...ux.ibm.com" <sidraya@...ux.ibm.com>, "wenjia@...ux.ibm.com"
	<wenjia@...ux.ibm.com>, "mjambigi@...ux.ibm.com" <mjambigi@...ux.ibm.com>,
	"tonylu@...ux.alibaba.com" <tonylu@...ux.alibaba.com>,
	"guwen@...ux.alibaba.com" <guwen@...ux.alibaba.com>, "davem@...emloft.net"
	<davem@...emloft.net>, "edumazet@...gle.com" <edumazet@...gle.com>,
	"kuba@...nel.org" <kuba@...nel.org>, "pabeni@...hat.com" <pabeni@...hat.com>,
	"horms@...nel.org" <horms@...nel.org>, "guangguan.wang@...ux.alibaba.com"
	<guangguan.wang@...ux.alibaba.com>, "linux-rdma@...r.kernel.org"
	<linux-rdma@...r.kernel.org>, "linux-s390@...r.kernel.org"
	<linux-s390@...r.kernel.org>, "netdev@...r.kernel.org"
	<netdev@...r.kernel.org>
Subject: RE: [PATCH net] net/smc: fix one NULL pointer dereference in
 smc_ib_is_sg_need_sync()



> -----Original Message-----
> From: D. Wythe [mailto:alibuda@...ux.alibaba.com]
> Sent: Tuesday, August 26, 2025 5:42 PM
> To: liujian (CE) <liujian56@...wei.com>
> Cc: alibuda@...ux.alibaba.com; dust.li@...ux.alibaba.com;
> sidraya@...ux.ibm.com; wenjia@...ux.ibm.com; mjambigi@...ux.ibm.com;
> tonylu@...ux.alibaba.com; guwen@...ux.alibaba.com;
> davem@...emloft.net; edumazet@...gle.com; kuba@...nel.org;
> pabeni@...hat.com; horms@...nel.org;
> guangguan.wang@...ux.alibaba.com; linux-rdma@...r.kernel.org; linux-
> s390@...r.kernel.org; netdev@...r.kernel.org
> Subject: Re: [PATCH net] net/smc: fix one NULL pointer dereference in
> smc_ib_is_sg_need_sync()
> 
> On Tue, Aug 26, 2025 at 04:44:42PM +0800, Liu Jian wrote:
> > BUG: kernel NULL pointer dereference, address: 00000000000002ec PGD 0
> > P4D 0
> > Oops: Oops: 0000 [#1] SMP PTI
> > CPU: 28 UID: 0 PID: 343 Comm: kworker/28:1 Kdump: loaded Tainted: G
> OE       6.17.0-rc2+ #9 NONE
> > Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE Hardware name:
> QEMU
> > Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014
> > Workqueue: smc_hs_wq smc_listen_work [smc]
> > RIP: 0010:smc_ib_is_sg_need_sync+0x9e/0xd0 [smc]
> >
> > diff --git a/net/smc/smc_ib.c b/net/smc/smc_ib.c index
> > 53828833a3f7..85501d2c1f1b 100644
> > --- a/net/smc/smc_ib.c
> > +++ b/net/smc/smc_ib.c
> > @@ -747,6 +747,8 @@ bool smc_ib_is_sg_need_sync(struct smc_link *lnk,
> >  		    buf_slot->sgt[lnk->link_idx].nents, i) {
> >  		if (!sg_dma_len(sg))
> >  			break;
> > +		if (!lnk->smcibdev->ibdev->dma_device)
> > +			break;
> 
> Why check it inside the loop?
Ok, will send v2, move the check outside of loop.
Thanks.