netdev - [Patch net] net_sched: keep alloc_hash updated after hash allocation

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Message-Id: <20200312054228.29688-2-xiyou.wangcong@gmail.com>
Date:   Wed, 11 Mar 2020 22:42:28 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     netdev@...r.kernel.org
Cc:     Cong Wang <xiyou.wangcong@...il.com>,
        syzbot+dcc34d54d68ef7d2d53d@...kaller.appspotmail.com,
        syzbot+c72da7b9ed57cde6fca2@...kaller.appspotmail.com,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Jiri Pirko <jiri@...nulli.us>
Subject: [Patch net] net_sched: keep alloc_hash updated after hash allocation

In commit 599be01ee567 ("net_sched: fix an OOB access in cls_tcindex")
I moved cp->hash calculation before the first
tcindex_alloc_perfect_hash(), but cp->alloc_hash is left untouched.
This difference could lead to another out of bound access.

cp->alloc_hash should always be the size allocated, we should
update it after this tcindex_alloc_perfect_hash().

Reported-and-tested-by: syzbot+dcc34d54d68ef7d2d53d@...kaller.appspotmail.com
Reported-and-tested-by: syzbot+c72da7b9ed57cde6fca2@...kaller.appspotmail.com
Fixes: 599be01ee567 ("net_sched: fix an OOB access in cls_tcindex")
Cc: Jamal Hadi Salim <jhs@...atatu.com>
Cc: Jiri Pirko <jiri@...nulli.us>
Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>
---
 net/sched/cls_tcindex.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/sched/cls_tcindex.c b/net/sched/cls_tcindex.c
index f2cb24b6f0cf..9904299424a1 100644
--- a/net/sched/cls_tcindex.c
+++ b/net/sched/cls_tcindex.c
@@ -359,6 +359,7 @@ tcindex_set_parms(struct net *net, struct tcf_proto *tp, unsigned long base,
 
 		if (tcindex_alloc_perfect_hash(net, cp) < 0)
 			goto errout;
+		cp->alloc_hash = cp->hash;
 		for (i = 0; i < min(cp->hash, p->hash); i++)
 			cp->perfect[i].res = p->perfect[i].res;
 		balloc = 1;
-- 
2.21.1