linux-kernel - [PATCH 5.8 030/177] RDMA/core: Fix unsafe linked list traversal after failing to allocate CQ

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Date:   Tue, 15 Sep 2020 16:11:41 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Xi Wang <wangxi11@...wei.com>,
        Weihang Li <liweihang@...wei.com>,
        Jason Gunthorpe <jgg@...dia.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.8 030/177] RDMA/core: Fix unsafe linked list traversal after failing to allocate CQ

From: Xi Wang <wangxi11@...wei.com>

[ Upstream commit 8aa64be019567c4f90d45c5082a4b6f22e182d00 ]

It's not safe to access the next CQ in list_for_each_entry() after
invoking ib_free_cq(), because the CQ has already been freed in current
iteration.  It should be replaced by list_for_each_entry_safe().

Fixes: c7ff819aefea ("RDMA/core: Introduce shared CQ pool API")
Link: https://lore.kernel.org/r/1598963935-32335-1-git-send-email-liweihang@huawei.com
Signed-off-by: Xi Wang <wangxi11@...wei.com>
Signed-off-by: Weihang Li <liweihang@...wei.com>
Reviewed-by: Jason Gunthorpe <jgg@...dia.com>
Signed-off-by: Jason Gunthorpe <jgg@...dia.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/infiniband/core/cq.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/core/cq.c b/drivers/infiniband/core/cq.c
index 513825e424bff..a92fc3f90bb5b 100644
--- a/drivers/infiniband/core/cq.c
+++ b/drivers/infiniband/core/cq.c
@@ -379,7 +379,7 @@ static int ib_alloc_cqs(struct ib_device *dev, unsigned int nr_cqes,
 {
 	LIST_HEAD(tmp_list);
 	unsigned int nr_cqs, i;
-	struct ib_cq *cq;
+	struct ib_cq *cq, *n;
 	int ret;
 
 	if (poll_ctx > IB_POLL_LAST_POOL_TYPE) {
@@ -412,7 +412,7 @@ static int ib_alloc_cqs(struct ib_device *dev, unsigned int nr_cqes,
 	return 0;
 
 out_free_cqs:
-	list_for_each_entry(cq, &tmp_list, pool_entry) {
+	list_for_each_entry_safe(cq, n, &tmp_list, pool_entry) {
 		cq->shared = false;
 		ib_free_cq(cq);
 	}
-- 
2.25.1