linux-kernel - [PATCH] uverbs: prevent potential underflow

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Message-ID: <20191005052337.GA20129@mwanda>
Date:   Sat, 5 Oct 2019 08:23:37 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Doug Ledford <dledford@...hat.com>,
        Potnuri Bharat Teja <bharat@...lsio.com>,
        Matan Barak <matanb@...lanox.com>
Cc:     Jason Gunthorpe <jgg@...pe.ca>, Leon Romanovsky <leon@...nel.org>,
        Shamir Rabinovitch <shamir.rabinovitch@...cle.com>,
        Matthew Wilcox <willy@...radead.org>,
        Michael Guralnik <michaelgur@...lanox.com>,
        linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: [PATCH] uverbs: prevent potential underflow

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 that "attr.comp_vector" whether 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.

Fixes: 9ee79fce3642 ("IB/core: Add completion queue (cq) object actions")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
---
 drivers/infiniband/core/uverbs.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/infiniband/core/uverbs.h b/drivers/infiniband/core/uverbs.h
index 1e5aeb39f774..63f7f7db5902 100644
--- a/drivers/infiniband/core/uverbs.h
+++ b/drivers/infiniband/core/uverbs.h
@@ -98,7 +98,7 @@ ib_uverbs_init_udata_buf_or_null(struct ib_udata *udata,
 
 struct ib_uverbs_device {
 	atomic_t				refcount;
-	int					num_comp_vectors;
+	u32					num_comp_vectors;
 	struct completion			comp;
 	struct device				dev;
 	/* First group for device attributes, NULL terminated array */
-- 
2.20.1