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

From: Leon Romanovsky <[email-masked]>
Date: Sun, 24 Jun 2018 11:23:47 +0300

From: Leon Romanovsky <[email-masked]>

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 <[email-masked]>
---
 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