RDMA/uverbs: Prevent potential underflow

BugLink: https://bugs.launchpad.net/bugs/1853519
[ 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@oracle.com>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/infiniband/core/uverbs.h b/drivers/infiniband/core/uverbs.h
index deccefb71a6b294efade714777f5d627345e41b0..3eac701e32db9531676a5aed97c6379756322e6d 100644 (file)
--- a/drivers/infiniband/core/uverbs.h
+++ b/drivers/infiniband/core/uverbs.h
@@ -94,7 +94,7 @@ 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;
        struct ib_device        __rcu          *ib_dev;

diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index be88fef7ae1b0efdc4a78970d4da7c639fa21a40..4610ef45237aa262c8f001d73ceef0aaac197537 100644 (file)
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -308,7 +308,7 @@ enum ib_cq_creation_flags {
 
 struct ib_cq_init_attr {
        unsigned int    cqe;
-       int             comp_vector;
+       u32             comp_vector;
        u32             flags;
 };