linux-kernel - [PATCH 5.10 382/663] RDMA/rtrs-srv: Do not pass a valid pointer to PTR

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Date:   Mon,  1 Mar 2021 17:10:30 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, kernel test robot <lkp@...el.com>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Jack Wang <jinpu.wang@...ud.ionos.com>,
        Jason Gunthorpe <jgg@...dia.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.10 382/663] RDMA/rtrs-srv: Do not pass a valid pointer to PTR_ERR()

From: Jack Wang <jinpu.wang@...ud.ionos.com>

[ Upstream commit ed408529679737a9a7ad816c8de5d59ba104bb11 ]

smatch gives the warning:

  drivers/infiniband/ulp/rtrs/rtrs-srv.c:1805 rtrs_rdma_connect() warn: passing zero to 'PTR_ERR'

Which is trying to say smatch has shown that srv is not an error pointer
and thus cannot be passed to PTR_ERR.

The solution is to move the list_add() down after full initilization of
rtrs_srv. To avoid holding the srv_mutex too long, only hold it during the
list operation as suggested by Leon.

Fixes: 03e9b33a0fd6 ("RDMA/rtrs: Only allow addition of path to an already established session")
Link: https://lore.kernel.org/r/20210216143807.65923-1-jinpu.wang@cloud.ionos.com
Reported-by: kernel test robot <lkp@...el.com>
Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Jack Wang <jinpu.wang@...ud.ionos.com>
Signed-off-by: Jason Gunthorpe <jgg@...dia.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/infiniband/ulp/rtrs/rtrs-srv.c | 20 +++++++-------------
 1 file changed, 7 insertions(+), 13 deletions(-)

diff --git a/drivers/infiniband/ulp/rtrs/rtrs-srv.c b/drivers/infiniband/ulp/rtrs/rtrs-srv.c
index 717304c49d0c3..f009a6907169c 100644
--- a/drivers/infiniband/ulp/rtrs/rtrs-srv.c
+++ b/drivers/infiniband/ulp/rtrs/rtrs-srv.c
@@ -1364,21 +1364,18 @@ static struct rtrs_srv *get_or_create_srv(struct rtrs_srv_ctx *ctx,
 			return srv;
 		}
 	}
+	mutex_unlock(&ctx->srv_mutex);
 	/*
 	 * If this request is not the first connection request from the
 	 * client for this session then fail and return error.
 	 */
-	if (!first_conn) {
-		mutex_unlock(&ctx->srv_mutex);
+	if (!first_conn)
 		return ERR_PTR(-ENXIO);
-	}
 
 	/* need to allocate a new srv */
 	srv = kzalloc(sizeof(*srv), GFP_KERNEL);
-	if  (!srv) {
-		mutex_unlock(&ctx->srv_mutex);
+	if  (!srv)
 		return ERR_PTR(-ENOMEM);
-	}
 
 	INIT_LIST_HEAD(&srv->paths_list);
 	mutex_init(&srv->paths_mutex);
@@ -1388,8 +1385,6 @@ static struct rtrs_srv *get_or_create_srv(struct rtrs_srv_ctx *ctx,
 	srv->ctx = ctx;
 	device_initialize(&srv->dev);
 	srv->dev.release = rtrs_srv_dev_release;
-	list_add(&srv->ctx_list, &ctx->srv_list);
-	mutex_unlock(&ctx->srv_mutex);
 
 	srv->chunks = kcalloc(srv->queue_depth, sizeof(*srv->chunks),
 			      GFP_KERNEL);
@@ -1402,6 +1397,9 @@ static struct rtrs_srv *get_or_create_srv(struct rtrs_srv_ctx *ctx,
 			goto err_free_chunks;
 	}
 	refcount_set(&srv->refcount, 1);
+	mutex_lock(&ctx->srv_mutex);
+	list_add(&srv->ctx_list, &ctx->srv_list);
+	mutex_unlock(&ctx->srv_mutex);
 
 	return srv;
 
@@ -1816,11 +1814,7 @@ static int rtrs_rdma_connect(struct rdma_cm_id *cm_id,
 	}
 	recon_cnt = le16_to_cpu(msg->recon_cnt);
 	srv = get_or_create_srv(ctx, &msg->paths_uuid, msg->first_conn);
-	/*
-	 * "refcount == 0" happens if a previous thread calls get_or_create_srv
-	 * allocate srv, but chunks of srv are not allocated yet.
-	 */
-	if (IS_ERR(srv) || refcount_read(&srv->refcount) == 0) {
+	if (IS_ERR(srv)) {
 		err = PTR_ERR(srv);
 		goto reject_w_err;
 	}
-- 
2.27.0