drm/amdkfd: Fix out-of-bounds write in kfd_event_page_set()

drm/amdkfd: Fix out-of-bounds write in kfd_event_page_set()

[ Upstream commit 8a70a26c9f34baea6c3199a9862ddaff4554a96d ]

The kfd_event_page_set() function writes KFD_SIGNAL_EVENT_LIMIT * 8
bytes via memset without checking the buffer size parameter. This allows
unprivileged userspace to trigger an out-of bounds kernel memory write
by passing a small buffer, leading to  potential privilege
escalation.

Signed-off-by: Sunday Clement <Sunday.Clement@amd.com>
Reviewed-by: Alexander Deucher <Alexander.Deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>