RDMA/ucm: Mark UCM interface as BROKEN

commit 7a8690ed upstream.

In commit 357d23c811a7 ("Remove the obsolete libibcm library")
in rdma-core [1], we removed obsolete library which used the
/dev/infiniband/ucmX interface.

Following multiple syzkaller reports about non-sanitized
user input in the UCMA module, the short audit reveals the same
issues in UCM module too.

It is better to disable this interface in the kernel,
before syzkaller team invests time and energy to harden
this unused interface.

[1] https://github.com/linux-rdma/rdma-core/pull/279Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/infiniband/Kconfig

@@ -33,6 +33,18 @@ config INFINIBAND_USER_ACCESS
 	  libibverbs, libibcm and a hardware driver library from
 	  <http://www.openfabrics.org/git/>.
 
+config INFINIBAND_USER_ACCESS_UCM
+	bool "Userspace CM (UCM, DEPRECATED)"
+	depends on BROKEN
+	depends on INFINIBAND_USER_ACCESS
+	help
+	  The UCM module has known security flaws, which no one is
+	  interested to fix. The user-space part of this code was
+	  dropped from the upstream a long time ago.
+
+	  This option is DEPRECATED and planned to be removed.
+
+
 config INFINIBAND_USER_MEM
 	bool
 	depends on INFINIBAND_USER_ACCESS != n

drivers/infiniband/core/Makefile

@@ -5,8 +5,8 @@ obj-$(CONFIG_INFINIBAND) +=		ib_core.o ib_mad.o ib_sa.o \
 					ib_cm.o iw_cm.o ib_addr.o \
 					$(infiniband-y)
 obj-$(CONFIG_INFINIBAND_USER_MAD) +=	ib_umad.o
-obj-$(CONFIG_INFINIBAND_USER_ACCESS) +=	ib_uverbs.o ib_ucm.o \
-					$(user_access-y)
+obj-$(CONFIG_INFINIBAND_USER_ACCESS) += ib_uverbs.o $(user_access-y)
+obj-$(CONFIG_INFINIBAND_USER_ACCESS_UCM) += ib_ucm.o $(user_access-y)
 
 ib_core-y :=			packer.o ud_header.o verbs.o sysfs.o \
 				device.o fmr_pool.o cache.o netlink.o \