4.9-stable review patch. If anyone has any objections, please let me know.
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From: Craig Dillabaugh cdillaba@mojatatu.com
[ Upstream commit 734549eb550c0c720bc89e50501f1b1e98cdd841 ]
Fixes a bug in the tcf_dump_walker function that can cause some actions to not be reported when dumping a large number of actions. This issue became more aggrevated when cookies feature was added. In particular this issue is manifest when large cookie values are assigned to the actions and when enough actions are created that the resulting table must be dumped in multiple batches.
The number of actions returned in each batch is limited by the total number of actions and the memory buffer size. With small cookies the numeric limit is reached before the buffer size limit, which avoids the code path triggering this bug. When large cookies are used buffer fills before the numeric limit, and the erroneous code path is hit.
For example after creating 32 csum actions with the cookie aaaabbbbccccdddd
$ tc actions ls action csum total acts 26
action order 0: csum (tcp) action continue index 1 ref 1 bind 0 cookie aaaabbbbccccdddd
.....
action order 25: csum (tcp) action continue index 26 ref 1 bind 0 cookie aaaabbbbccccdddd total acts 6
action order 0: csum (tcp) action continue index 28 ref 1 bind 0 cookie aaaabbbbccccdddd
......
action order 5: csum (tcp) action continue index 32 ref 1 bind 0 cookie aaaabbbbccccdddd
Note that the action with index 27 is omitted from the report.
Fixes: 4b3550ef530c ("[NET_SCHED]: Use nla_nest_start/nla_nest_end")" Signed-off-by: Craig Dillabaugh cdillaba@mojatatu.com Acked-by: Jamal Hadi Salim jhs@mojatatu.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/sched/act_api.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/net/sched/act_api.c +++ b/net/sched/act_api.c @@ -95,8 +95,10 @@ static int tcf_dump_walker(struct tcf_ha continue;
nest = nla_nest_start(skb, n_i); - if (nest == NULL) + if (nest == NULL) { + index--; goto nla_put_failure; + } err = tcf_action_dump_1(skb, p, 0, 0); if (err < 0) { index--;