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

Greg Kroah-Hartman
2020-09-15T23:34:45Z

From: Xi Wang <wangxi11@huawei.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@huawei.com>
Signed-off-by: Weihang Li <liweihang@huawei.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.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