[PATCH 4.14 074/105] RDMA/uverbs: Prevent potential underflow

From: Greg Kroah-Hartman
Date: Mon Nov 11 2019 - 14:07:02 EST


From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

[ Upstream commit a9018adfde809d44e71189b984fa61cc89682b5e ]

The issue is in drivers/infiniband/core/uverbs_std_types_cq.c in the
UVERBS_HANDLER(UVERBS_METHOD_CQ_CREATE) function. We check that:

if (attr.comp_vector >= attrs->ufile->device->num_comp_vectors) {

But we don't check if "attr.comp_vector" is negative. It could
potentially lead to an array underflow. My concern would be where
cq->vector is used in the create_cq() function from the cxgb4 driver.

And really "attr.comp_vector" is appears as a u32 to user space so that's
the right type to use.

Fixes: 9ee79fce3642 ("IB/core: Add completion queue (cq) object actions")
Link: https://lore.kernel.org/r/20191011133419.GA22905@mwanda
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/infiniband/core/uverbs.h | 2 +-
include/rdma/ib_verbs.h | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/core/uverbs.h b/drivers/infiniband/core/uverbs.h
index 37c8903e7fd0c..8d79a48ccd388 100644
--- a/drivers/infiniband/core/uverbs.h
+++ b/drivers/infiniband/core/uverbs.h
@@ -87,7 +87,7 @@

struct ib_uverbs_device {
atomic_t refcount;
- int num_comp_vectors;
+ u32 num_comp_vectors;
struct completion comp;
struct device *dev;
struct ib_device __rcu *ib_dev;
diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index b8a5118b6a428..4a43193319894 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -306,7 +306,7 @@ enum ib_cq_creation_flags {

struct ib_cq_init_attr {
unsigned int cqe;
- int comp_vector;
+ u32 comp_vector;
u32 flags;
};

--
2.20.1