netdev - [PATCH rdma-next 06/12] RDMA/uverbs: Don't overwrite NULL pointer with ZERO_SIZE

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Date:   Sun, 24 Jun 2018 11:23:47 +0300
From:   Leon Romanovsky <leon@...nel.org>
To:     Doug Ledford <dledford@...hat.com>,
        Jason Gunthorpe <jgg@...lanox.com>
Cc:     Leon Romanovsky <leonro@...lanox.com>,
        RDMA mailing list <linux-rdma@...r.kernel.org>,
        Hadar Hen Zion <hadarh@...lanox.com>,
        Matan Barak <matanb@...lanox.com>,
        Michael J Ruhl <michael.j.ruhl@...el.com>,
        Noa Osherovich <noaos@...lanox.com>,
        Raed Salem <raeds@...lanox.com>,
        Yishai Hadas <yishaih@...lanox.com>,
        Saeed Mahameed <saeedm@...lanox.com>,
        linux-netdev <netdev@...r.kernel.org>
Subject: [PATCH rdma-next 06/12] RDMA/uverbs: Don't overwrite NULL pointer with ZERO_SIZE_PTR

From: Leon Romanovsky <leonro@...lanox.com>

Number of specs is provided by user and in valid case can be equal to zero.
Such argument causes to call to kcalloc() with zero-length request and in
return the ZERO_SIZE_PTR is assigned. This pointer is different from NULL
and makes various if (..) checks to success.

Fixes: b6ba4a9aa59f ("IB/uverbs: Add support for flow counters")
Signed-off-by: Leon Romanovsky <leonro@...lanox.com>
---
 drivers/infiniband/core/uverbs_cmd.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
index 3aba63aa1779..8ed4b674416f 100644
--- a/drivers/infiniband/core/uverbs_cmd.c
+++ b/drivers/infiniband/core/uverbs_cmd.c
@@ -2768,6 +2768,9 @@ static struct ib_uflow_resources *flow_resources_alloc(size_t num_specs)
 	if (!resources)
 		return NULL;
 
+	if (!num_specs)
+		goto out;
+
 	resources->counters =
 		kcalloc(num_specs, sizeof(*resources->counters), GFP_KERNEL);
 	resources->collection =
@@ -2776,8 +2779,8 @@ static struct ib_uflow_resources *flow_resources_alloc(size_t num_specs)
 	if (!resources->counters || !resources->collection)
 		goto err;
 
+out:
 	resources->max = num_specs;
-
 	return resources;
 
 err:
-- 
2.14.4