On Thu, Aug 28, 2025 at 08:41:17PM +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]
> ...
> 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@xxxxxxxxxx>
> ---
> v1->v2:
> move the check outside of loop.
> net/smc/smc_ib.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/net/smc/smc_ib.c b/net/smc/smc_ib.c
> index 53828833a3f7..a42ef3f77b96 100644
> --- a/net/smc/smc_ib.c
> +++ b/net/smc/smc_ib.c
> @@ -742,6 +742,9 @@ bool smc_ib_is_sg_need_sync(struct smc_link *lnk,
> unsigned int i;
> bool ret = false;
>
> + if (!lnk->smcibdev->ibdev->dma_device)
> + return ret;
> +
> /* for now there is just one DMA address */
> for_each_sg(buf_slot->sgt[lnk->link_idx].sgl, sg,
> buf_slot->sgt[lnk->link_idx].nents, i) {
LGTM, thanks.
Reviewed-by: D. Wythe <alibuda@xxxxxxxxxxxxxxxxx>
