RDMA/ucma: Introduce safer rdma_addr_size() variants

There are several places in the ucma ABI where userspace can pass in a
sockaddr but set the address family to AF_IB.  When that happens,
rdma_addr_size() will return a size bigger than sizeof struct sockaddr_in6,
and the ucma kernel code might end up copying past the end of a buffer
not sized for a struct sockaddr_ib.

Fix this by introducing new variants

    int rdma_addr_size_in6(struct sockaddr_in6 *addr);
    int rdma_addr_size_kss(struct __kernel_sockaddr_storage *addr);

that are type-safe for the types used in the ucma ABI and return 0 if the
size computed is bigger than the size of the type passed in.  We can use
these new variants to check what size userspace has passed in before
copying any addresses.

Reported-by: <syzbot+6800425d54ed3ed8135d@syzkaller.appspotmail.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/drivers/infiniband/core/addr.c b/drivers/infiniband/core/addr.c
index c3e6811bb1bd..cb1d2ab13c66 100644
--- a/drivers/infiniband/core/addr.c
+++ b/drivers/infiniband/core/addr.c
@@ -207,6 +207,22 @@ int rdma_addr_size(struct sockaddr *addr)
 }
 EXPORT_SYMBOL(rdma_addr_size);
 
+int rdma_addr_size_in6(struct sockaddr_in6 *addr)
+{
+	int ret = rdma_addr_size((struct sockaddr *) addr);
+
+	return ret <= sizeof(*addr) ? ret : 0;
+}
+EXPORT_SYMBOL(rdma_addr_size_in6);
+
+int rdma_addr_size_kss(struct __kernel_sockaddr_storage *addr)
+{
+	int ret = rdma_addr_size((struct sockaddr *) addr);
+
+	return ret <= sizeof(*addr) ? ret : 0;
+}
+EXPORT_SYMBOL(rdma_addr_size_kss);
+
 static struct rdma_addr_client self;
 
 void rdma_addr_register_client(struct rdma_addr_client *client)