[PATCH 4.19 06/36] qed/qed_dev: guard against a possible division by zero

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Daniil Tatianin <d-tatianin@yandex-team.ru>

[ Upstream commit 1a9dc5610ef89d807acdcfbff93a558f341a44da ]

Previously we would divide total_left_rate by zero if num_vports
happened to be 1 because non_requested_count is calculated as
num_vports - req_count. Guard against this by validating num_vports at
the beginning and returning an error otherwise.

Found by Linux Verification Center (linuxtesting.org) with the SVACE
static analysis tool.

Fixes: bcd197c81f63 ("qed: Add vport WFQ configuration APIs")
Signed-off-by: Daniil Tatianin <d-tatianin@yandex-team.ru>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/20230309201556.191392-1-d-tatianin@yandex-team.ru
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/ethernet/qlogic/qed/qed_dev.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/ethernet/qlogic/qed/qed_dev.c b/drivers/net/ethernet/qlogic/qed/qed_dev.c
index e50fc8f714dcf..7e5beb4136014 100644
--- a/drivers/net/ethernet/qlogic/qed/qed_dev.c
+++ b/drivers/net/ethernet/qlogic/qed/qed_dev.c
@@ -4062,6 +4062,11 @@ static int qed_init_wfq_param(struct qed_hwfn *p_hwfn,
 
 	num_vports = p_hwfn->qm_info.num_vports;
 
+	if (num_vports < 2) {
+		DP_NOTICE(p_hwfn, "Unexpected num_vports: %d\n", num_vports);
+		return -EINVAL;
+	}
+
 	/* Accounting for the vports which are configured for WFQ explicitly */
 	for (i = 0; i < num_vports; i++) {
 		u32 tmp_speed;
-- 
2.39.2