RDMA/uverbs: Guard legacy bundles without method_elm

The legacy write() path dispatches through a uverbs_api_write_method, but
the uverbs_attr_bundle passed to provider code does not have an ioctl
method element. If malformed provider input causes the common uverbs
validation code to emit an error message, uverbs_get_handler_fn()
dereferences the uninitialized method_elm pointer.

Initialize method_elm explicitly for legacy bundles and make
uverbs_get_handler_fn() return NULL when no ioctl method is present. The
legacy dispatcher continues to use its local write method, while the ioctl
path continues to use the registered ioctl handler.

Cc: stable@vger.kernel.org
Fixes: 7122ff96068a ("RDMA/core: Do not read wild stack memory in uverbs_get_handler_fn()")
Link: https://patch.msgid.link/r/AOYAQgCQK3IXqJLr1TB5Qao9.1.1787036796115.Hmail.242270054@hdu.edu.cn
Signed-off-by: Yuhang Pan <242270054@hdu.edu.cn>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

0 files changed, 0 insertions, 0 deletions