net/sched: act_simple: fix parsing of TCA_DEF_DATA

use nla_strlcpy() to avoid copying data beyond the length of TCA_DEF_DATA
netlink attribute, in case it is less than SIMP_MAX_DATA and it does not
end with '\0' character.

v2: fix errors in the commit message, thanks Hangbin Liu

Fixes: fa1b1cff3d06 ("net_cls_act: Make act_simple use of netlink policy.")
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 9 deletions

diff --git a/net/sched/act_simple.c b/net/sched/act_simple.c
index 9618b4a83cee..98c4afe7c15b 100644
--- a/net/sched/act_simple.c
+++ b/net/sched/act_simple.c
@@ -53,22 +53,22 @@ static void tcf_simp_release(struct tc_action *a)
         kfree(d->tcfd_defdata);
 }
 
-static int alloc_defdata(struct tcf_defact *d, char *defdata)
+static int alloc_defdata(struct tcf_defact *d, const struct nlattr *defdata)
 {
         d->tcfd_defdata = kzalloc(SIMP_MAX_DATA, GFP_KERNEL);
         if (unlikely(!d->tcfd_defdata))
                 return -ENOMEM;
-        strlcpy(d->tcfd_defdata, defdata, SIMP_MAX_DATA);
+        nla_strlcpy(d->tcfd_defdata, defdata, SIMP_MAX_DATA);
         return 0;
 }
 
-static void reset_policy(struct tcf_defact *d, char *defdata,
+static void reset_policy(struct tcf_defact *d, const struct nlattr *defdata,
                          struct tc_defact *p)
 {
         spin_lock_bh(&d->tcf_lock);
         d->tcf_action = p->action;
         memset(d->tcfd_defdata, 0, SIMP_MAX_DATA);
-        strlcpy(d->tcfd_defdata, defdata, SIMP_MAX_DATA);
+        nla_strlcpy(d->tcfd_defdata, defdata, SIMP_MAX_DATA);
         spin_unlock_bh(&d->tcf_lock);
 }
 
@@ -87,7 +87,6 @@ static int tcf_simp_init(struct net *net, struct nlattr *nla,
         struct tcf_defact *d;
         bool exists = false;
         int ret = 0, err;
-        char *defdata;
 
         if (nla == NULL)
                 return -EINVAL;
@@ -110,8 +109,6 @@ static int tcf_simp_init(struct net *net, struct nlattr *nla,
                 return -EINVAL;
         }
 
-        defdata = nla_data(tb[TCA_DEF_DATA]);
-
         if (!exists) {
                 ret = tcf_idr_create(tn, parm->index, est, a,
                                      &act_simp_ops, bind, false);
@@ -119,7 +116,7 @@ static int tcf_simp_init(struct net *net, struct nlattr *nla,
                         return ret;
 
                 d = to_defact(*a);
-                ret = alloc_defdata(d, defdata);
+                ret = alloc_defdata(d, tb[TCA_DEF_DATA]);
                 if (ret < 0) {
                         tcf_idr_release(*a, bind);
                         return ret;
@@ -133,7 +130,7 @@ static int tcf_simp_init(struct net *net, struct nlattr *nla,
                 if (!ovr)
                         return -EEXIST;
 
-                reset_policy(d, defdata, parm);
+                reset_policy(d, tb[TCA_DEF_DATA], parm);
         }
 
         if (ret == ACT_P_CREATED)