qed/qed_dev: guard against a possible division by zero

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>

diff --git a/drivers/net/ethernet/qlogic/qed/qed_dev.c b/drivers/net/ethernet/qlogic/qed/qed_dev.c
index d61cd32..86a93ca 100644 (file)
--- a/drivers/net/ethernet/qlogic/qed/qed_dev.c
+++ b/drivers/net/ethernet/qlogic/qed/qed_dev.c
@@ -5083,6 +5083,11 @@ 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;