netdev - [PATCH net-next] net: sched: Fix hw_stats

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Date:   Wed, 18 Mar 2020 19:42:29 +0200
From:   Petr Machata <petrm@...lanox.com>
To:     netdev@...r.kernel.org
Cc:     Petr Machata <petrm@...lanox.com>, Jiri Pirko <jiri@...lanox.com>,
        David Miller <davem@...emloft.net>
Subject: [PATCH net-next] net: sched: Fix hw_stats_type setting in pedit loop

In the commit referenced below, hw_stats_type of an entry is set for every
entry that corresponds to a pedit action. However, the assignment is only
done after the entry pointer is bumped, and therefore could overwrite
memory outside of the entries array.

The reason for this positioning may have been that the current entry's
hw_stats_type is already set above, before the action-type dispatch.
However, if there are no more actions, the assignment is wrong. And if
there are, the next round of the for_each_action loop will make the
assignment before the action-type dispatch anyway.

Therefore fix this issue by simply reordering the two lines.

Fixes: 74522e7baae2 ("net: sched: set the hw_stats_type in pedit loop")
Signed-off-by: Petr Machata <petrm@...lanox.com>
---
 net/sched/cls_api.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 259a2e51ef3e..ca46290c5809 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -3613,8 +3613,8 @@ int tc_setup_flow_action(struct flow_action *flow_action,
 				entry->mangle.mask = tcf_pedit_mask(act, k);
 				entry->mangle.val = tcf_pedit_val(act, k);
 				entry->mangle.offset = tcf_pedit_offset(act, k);
-				entry = &flow_action->entries[++j];
 				entry->hw_stats_type = act->hw_stats_type;
+				entry = &flow_action->entries[++j];
 			}
 		} else if (is_tcf_csum(act)) {
 			entry->id = FLOW_ACTION_CSUM;
-- 
2.20.1