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

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Message-ID: <20250826084442.322587-1-liujian56@huawei.com>
Date: Tue, 26 Aug 2025 16:44:42 +0800
From: Liu Jian <liujian56@...wei.com>
To: <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>
CC: <linux-rdma@...r.kernel.org>, <linux-s390@...r.kernel.org>,
	<netdev@...r.kernel.org>
Subject: [PATCH net] net/smc: fix one NULL pointer dereference in smc_ib_is_sg_need_sync()

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]
...
Call Trace:
 <TASK>
 smcr_buf_map_link+0x211/0x2a0 [smc]
 __smc_buf_create+0x522/0x970 [smc]
 smc_buf_create+0x3a/0x110 [smc]
 smc_find_rdma_v2_device_serv+0x18f/0x240 [smc]
 ? smc_vlan_by_tcpsk+0x7e/0xe0 [smc]
 smc_listen_find_device+0x1dd/0x2b0 [smc]
 smc_listen_work+0x30f/0x580 [smc]
 process_one_work+0x18c/0x340
 worker_thread+0x242/0x360
 kthread+0xe7/0x220
 ret_from_fork+0x13a/0x160
 ret_from_fork_asm+0x1a/0x30
 </TASK>

If the software RoCE device is used, ibdev->dma_device is a null pointer.
As a result, the problem occurs. Null pointer detection is added to
prevent problems.

Fixes: 0ef69e788411c ("net/smc: optimize for smc_sndbuf_sync_sg_for_device and smc_rmb_sync_sg_for_cpu")
Signed-off-by: Liu Jian <liujian56@...wei.com>
---
 net/smc/smc_ib.c | 2 ++
 1 file changed, 2 insertions(+)

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;
 		if (dma_need_sync(lnk->smcibdev->ibdev->dma_device,
 				  sg_dma_address(sg))) {
 			ret = true;
-- 
2.34.1