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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Jamal Hadi Salim <jhs@mojatatu.com>,
        Jiri Pirko <jiri@resnulli.us>,
        Cong Wang <xiyou.wangcong@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        syzbot+dcc34d54d68ef7d2d53d@syzkaller.appspotmail.com,
        syzbot+c72da7b9ed57cde6fca2@syzkaller.appspotmail.com
Subject: [PATCH 4.19 017/116] net_sched: keep alloc_hash updated after hash allocation
Date:   Wed,  1 Apr 2020 18:16:33 +0200
Message-Id: <20200401161544.257253191@linuxfoundation.org>
In-Reply-To: <20200401161542.669484650@linuxfoundation.org>
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From: Cong Wang <xiyou.wangcong@gmail.com>

[ Upstream commit 0d1c3530e1bd38382edef72591b78e877e0edcd3 ]

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@syzkaller.appspotmail.com
Reported-and-tested-by: syzbot+c72da7b9ed57cde6fca2@syzkaller.appspotmail.com
Fixes: 599be01ee567 ("net_sched: fix an OOB access in cls_tcindex")
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/sched/cls_tcindex.c |    1 +
 1 file changed, 1 insertion(+)

--- a/net/sched/cls_tcindex.c
+++ b/net/sched/cls_tcindex.c
@@ -357,6 +357,7 @@ tcindex_set_parms(struct net *net, struc
 
 		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;