linux-hardening - [PATCH][next] net: sched: Use struct

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Message-ID: <20210929201718.GA342296@embeddedor>
Date:   Wed, 29 Sep 2021 15:17:18 -0500
From:   "Gustavo A. R. Silva" <gustavoars@...nel.org>
To:     Stephen Hemminger <stephen@...workplumber.org>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Jiri Pirko <jiri@...nulli.us>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        linux-hardening@...r.kernel.org
Subject: [PATCH][next] net: sched: Use struct_size() helper in kvmalloc()

Make use of the struct_size() helper instead of an open-coded version,
in order to avoid any potential type mistakes or integer overflows
that, in the worst scenario, could lead to heap overflows.

Link: https://github.com/KSPP/linux/issues/160
Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
---
 net/sched/sch_netem.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index 0c345e43a09a..ecbb10db1111 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -785,7 +785,7 @@ static int get_dist_table(struct Qdisc *sch, struct disttable **tbl,
 	if (!n || n > NETEM_DIST_MAX)
 		return -EINVAL;
 
-	d = kvmalloc(sizeof(struct disttable) + n * sizeof(s16), GFP_KERNEL);
+	d = kvmalloc(struct_size(d, table, n), GFP_KERNEL);
 	if (!d)
 		return -ENOMEM;
 
-- 
2.27.0