| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.9 056/105] net/sched: cls_matchall: fix crash when used with classful qdisc | Date | Tue, 10 Oct 2017 21:50:27 +0200 |
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4.9-stable review patch. If anyone has any objections, please let me know.
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From: Davide Caratti <dcaratti@redhat.com>
[ Upstream commit 3ff4cbec87da48b0ec1f7b6196607b034de0c680 ]
this script, edited from Linux Advanced Routing and Traffic Control guide
tc q a dev en0 root handle 1: htb default a tc c a dev en0 parent 1: classid 1:1 htb rate 6mbit burst 15k tc c a dev en0 parent 1:1 classid 1:a htb rate 5mbit ceil 6mbit burst 15k tc c a dev en0 parent 1:1 classid 1:b htb rate 1mbit ceil 6mbit burst 15k tc f a dev en0 parent 1:0 prio 1 $clsname $clsargs classid 1:b ping $address -c1 tc -s c s dev en0
classifies traffic to 1:b or 1:a, depending on whether the packet matches or not the pattern $clsargs of filter $clsname. However, when $clsname is 'matchall', a systematic crash can be observed in htb_classify(). HTB and classful qdiscs don't assign initial value to struct tcf_result, but then they expect it to contain valid values after filters have been run. Thus, current 'matchall' ignores the TCA_MATCHALL_CLASSID attribute, configured by user, and makes HTB (and classful qdiscs) dereference random pointers.
By assigning head->res to *res in mall_classify(), before the actions are invoked, we fix this crash and enable TCA_MATCHALL_CLASSID functionality, that had no effect on 'matchall' classifier since its first introduction.
BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1460213 Reported-by: Jiri Benc <jbenc@redhat.com> Fixes: b87f7936a932 ("net/sched: introduce Match-all classifier") Signed-off-by: Davide Caratti <dcaratti@redhat.com> Acked-by: Yotam Gigi <yotamg@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- net/sched/cls_matchall.c | 1 + 1 file changed, 1 insertion(+)
--- a/net/sched/cls_matchall.c +++ b/net/sched/cls_matchall.c @@ -32,6 +32,7 @@ static int mall_classify(struct sk_buff if (tc_skip_sw(head->flags)) return -1; + *res = head->res; return tcf_exts_exec(skb, &head->exts, res); }
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