[PATCH AUTOSEL 5.10 033/100] drm/amdkfd: Fix UBSAN shift-out-of-bounds warning

Sasha Levin
2021-05-03T16:49:53Z

From: Anson Jacob <Anson.Jacob@amd.com>

[ Upstream commit 50e2fc36e72d4ad672032ebf646cecb48656efe0 ]

If get_num_sdma_queues or get_num_xgmi_sdma_queues is 0, we end up
doing a shift operation where the number of bits shifted equals
number of bits in the operand. This behaviour is undefined.

Set num_sdma_queues or num_xgmi_sdma_queues to ULLONG_MAX, if the
count is >= number of bits in the operand.

Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1472

Reported-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Anson Jacob <Anson.Jacob@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Tested-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
.../drm/amd/amdkfd/kfd_device_queue_manager.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c b/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
index 8e5cfb1f8a51..6ea8a4b6efde 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
@@ -1128,6 +1128,9 @@ static int set_sched_resources(struct device_queue_manager *dqm)

static int initialize_cpsch(struct device_queue_manager *dqm)
{
+ uint64_t num_sdma_queues;
+ uint64_t num_xgmi_sdma_queues;
+
pr_debug("num of pipes: %d\n", get_pipes_per_mec(dqm));

mutex_init(&dqm->lock_hidden);
@@ -1136,8 +1139,18 @@ static int initialize_cpsch(struct device_queue_manager *dqm)
dqm->active_cp_queue_count = 0;
dqm->gws_queue_count = 0;
dqm->active_runlist = false;
- dqm->sdma_bitmap = ~0ULL >> (64 - get_num_sdma_queues(dqm));
- dqm->xgmi_sdma_bitmap = ~0ULL >> (64 - get_num_xgmi_sdma_queues(dqm));
+
+ num_sdma_queues = get_num_sdma_queues(dqm);
+ if (num_sdma_queues >= BITS_PER_TYPE(dqm->sdma_bitmap))
+ dqm->sdma_bitmap = ULLONG_MAX;
+ else
+ dqm->sdma_bitmap = (BIT_ULL(num_sdma_queues) - 1);
+
+ num_xgmi_sdma_queues = get_num_xgmi_sdma_queues(dqm);
+ if (num_xgmi_sdma_queues >= BITS_PER_TYPE(dqm->xgmi_sdma_bitmap))
+ dqm->xgmi_sdma_bitmap = ULLONG_MAX;
+ else
+ dqm->xgmi_sdma_bitmap = (BIT_ULL(num_xgmi_sdma_queues) - 1);

INIT_WORK(&dqm->hw_exception_work, kfd_process_hw_exception);

--
2.30.2