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Message-ID: <ca74a481-3e80-9a7a-9db7-d766a16d8fd6@acm.org>
Date:   Tue, 30 Aug 2022 21:04:47 -0700
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Subject: Re: [PATCH] RDMA/srp: Set scmnd->result only when scmnd is not NULL
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To:     "yangx.jy@fujitsu.com" <yangx.jy@fujitsu.com>,
        "jgg@nvidia.com" <jgg@nvidia.com>,
        "leon@kernel.org" <leon@kernel.org>
Cc:     "linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
References: <20220831014730.17566-1-yangx.jy@fujitsu.com>
 <5daac9db-2b34-fbe5-a891-8ecf77fbe46f@acm.org>
 <bff7565b-7159-e8f4-e8f5-711994f95056@fujitsu.com>
From:   Bart Van Assche <bvanassche@acm.org>
In-Reply-To: <bff7565b-7159-e8f4-e8f5-711994f95056@fujitsu.com>
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On 8/30/22 20:16, yangx.jy@fujitsu.com wrote:
> Sorry, I didn't make the right fix. I will send v2 patch.
> I think scmnd may be set to NULL after srp_claim_req() is called and
> then setting scmnd->result can trigger the NULL pointer dereference.

Something like this untested patch may be what you are looking for:

diff --git a/drivers/infiniband/ulp/srp/ib_srp.c 
b/drivers/infiniband/ulp/srp/ib_srp.c
index 7720ea270ed8..d7f69e593a63 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -1961,7 +1961,8 @@ static void srp_process_rsp(struct srp_rdma_ch 
*ch, struct srp_rsp *rsp)
  		if (scmnd) {
  			req = scsi_cmd_priv(scmnd);
  			scmnd = srp_claim_req(ch, req, NULL, scmnd);
-		} else {
+		}
+		if (!scmnd) {
  			shost_printk(KERN_ERR, target->scsi_host,
  				     "Null scmnd for RSP w/tag %#016llx received on ch %td / QP 
%#x\n",
  				     rsp->tag, ch - target->ch, ch->qp->qp_num);

Bart.