linux-kernel - [PATCH AUTOSEL 5.12 050/134] drm/amdkfd: Fix UBSAN shift-out-of-bounds warning

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Message-Id: <20210503163513.2851510-50-sashal@kernel.org>
Date:   Mon,  3 May 2021 12:33:49 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Anson Jacob <Anson.Jacob@....com>, Lyude Paul <lyude@...hat.com>,
        Alex Deucher <alexander.deucher@....com>,
        Felix Kuehling <Felix.Kuehling@....com>,
        Sasha Levin <sashal@...nel.org>, amd-gfx@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 5.12 050/134] drm/amdkfd: Fix UBSAN shift-out-of-bounds warning

From: Anson Jacob <Anson.Jacob@....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@...hat.com>
Signed-off-by: Anson Jacob <Anson.Jacob@....com>
Reviewed-by: Alex Deucher <alexander.deucher@....com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@....com>
Tested-by: Lyude Paul <lyude@...hat.com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.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 4598a9a58125..a4266c4bca13 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