After our server is upgraded to a newer kernel, we found that it continuesly print a warning in the kernel message. The warning is, [832984.946322] netlink: 'irmas.lc': attribute type 1 has an invalid length.

irmas.lc is one of our container monitor daemons, and it will use CGROUPSTATS_CMD_GET to get the cgroupstats, that is similar with tools/accounting/getdelays.c. We can also produce this warning with getdelays. For example, after running bellow command $ ./getdelays -C /sys/fs/cgroup/memory then you can find a warning in dmesg, [61607.229318] netlink: 'getdelays': attribute type 1 has an invalid length.

This warning is introduced in commit 6e237d099fac ("netlink: Relax attr validation for fixed length types"), which is used to check whether attributes using types NLA_U* and NLA_S* have an exact length.

Regarding this issue, the root cause is cgroupstats_cmd_get_policy defines a wrong type as NLA_U32, while it should be NLA_NESTED an its minimal length is NLA_HDRLEN. That is similar to taskstats_cmd_get_policy.

As this behavior change really breaks our application, we'd better cc stable as well.

Signed-off-by: Yafang Shao laoar.shao@gmail.com Cc: stable@vger.kernel.org --- kernel/taskstats.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/taskstats.c b/kernel/taskstats.c index e2ac0e3..b90a520 100644 --- a/kernel/taskstats.c +++ b/kernel/taskstats.c @@ -35,8 +35,8 @@ static struct genl_family family;

static const struct nla_policy taskstats_cmd_get_policy[TASKSTATS_CMD_ATTR_MAX+1] = { - [TASKSTATS_CMD_ATTR_PID] = { .type = NLA_U32 }, - [TASKSTATS_CMD_ATTR_TGID] = { .type = NLA_U32 }, + [TASKSTATS_CMD_ATTR_PID] = { .type = NLA_NESTED }, + [TASKSTATS_CMD_ATTR_TGID] = { .type = NLA_NESTED }, [TASKSTATS_CMD_ATTR_REGISTER_CPUMASK] = { .type = NLA_STRING }, [TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK] = { .type = NLA_STRING },};

@@ -45,7 +45,7 @@ * Make sure they are always aligned. */ static const struct nla_policy cgroupstats_cmd_get_policy[TASKSTATS_CMD_ATTR_MAX+1] = { - [CGROUPSTATS_CMD_ATTR_FD] = { .type = NLA_U32 }, + [CGROUPSTATS_CMD_ATTR_FD] = { .type = NLA_NESTED }, };

struct listener {