RDMA/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 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>

diff --git a/drivers/infiniband/core/uverbs.h b/drivers/infiniband/core/uverbs.h
index 1e5aeb3..63f7f7d 100644 (file)
--- 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 */

diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index 6a47ba8..e7e733a 100644 (file)
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -366,7 +366,7 @@ struct ib_tm_caps {
 
 struct ib_cq_init_attr {
        unsigned int    cqe;
-       int             comp_vector;
+       u32             comp_vector;
        u32             flags;
 };