In the Linux kernel, the following vulnerability has been resolved: RDMA/mad: Fix receive buffer leak when PKey enforcement fails ib_mad_c

In the Linux kernel, the following vulnerability has been resolved:

RDMA/mad: Fix receive buffer leak when PKey enforcement fails

ib_mad_complete_recv() initializes mad_recv_wc->rmpp_list and then runs
ib_mad_enforce_security() before linking recv_buf onto that list. On
failure it calls ib_free_recv_mad(), which only walks rmpp_list and frees
the ib_mad_private of every buffer found there. As the list is still
empty at that point, nothing is freed at all.

The caller cannot clean up either: ib_mad_recv_done() sets recv to NULL
right after ib_mad_complete_recv() returns, assuming the MAD layer took
ownership of the buffer. Every MAD that fails the PKey check therefore
leaks one ib_mad_private (about 300 bytes per IB port MAD, ~2K for OPA),
and a remote node can trigger this repeatedly by sending MADs with a
wrong PKey.

Link recv_buf onto rmpp_list right after the list is initialized, so the
error path has something to free.