Merge branch 'cls_u32-fix-refcount-leak'
Davide Caratti says: ==================== net/sched: cls_u32: fix refcount leak a refcount leak in the error path of u32_change() has been recently introduced. It can be observed with the following commands: [root@f31 ~]# tc filter replace dev eth0 ingress protocol ip prio 97 \ > u32 match ip src 127.0.0.1/32 indev notexist20 flowid 1:1 action drop RTNETLINK answers: Invalid argument We have an error talking to the kernel [root@f31 ~]# tc filter replace dev eth0 ingress protocol ip prio 98 \ > handle 42:42 u32 divisor 256 Error: cls_u32: Divisor can only be used on a hash table. We have an error talking to the kernel [root@f31 ~]# tc filter replace dev eth0 ingress protocol ip prio 99 \ > u32 ht 47:47 Error: cls_u32: Specified hash table not found. We have an error talking to the kernel they all legitimately return -EINVAL; however, they leave semi-configured filters at eth0 tc ingress: [root@f31 ~]# tc filter show dev eth0 ingress filter protocol ip pref 97 u32 chain 0 filter protocol ip pref 97 u32 chain 0 fh 800: ht divisor 1 filter protocol ip pref 98 u32 chain 0 filter protocol ip pref 98 u32 chain 0 fh 801: ht divisor 1 filter protocol ip pref 99 u32 chain 0 filter protocol ip pref 99 u32 chain 0 fh 802: ht divisor 1 With older kernels, filters were unconditionally considered empty (and thus de-refcounted) on the error path of ->change(). After commit 8b64678e ("net: sched: refactor tp insert/delete for concurrent execution"), filters were considered empty when the walk() function didn't set 'walker.stop' to 1. Finally, with commit 6676d5e4 ("net: sched: set dedicated tcf_walker flag when tp is empty"), tc filters are considered empty unless the walker function is called with a non-NULL handle. This last change doesn't fit cls_u32 design, because at least the "root hnode" is (almost) always non-NULL, as it's allocated in u32_init(). - patch 1/2 is a proposal to restore the original kernel behavior, where no filter was installed in the error path of u32_change(). - patch 2/2 adds tdc selftests that can be ued to verify the correct behavior of u32 in the error path of ->change(). ==================== Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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