3.16.42-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Amir Vadai <amir@xxxxxxxx>
[ Upstream commit 95c2027bfeda21a28eb245121e6a249f38d0788e ]
Add a validation function to make sure offset is valid:
1. Not below skb head (could happen when offset is negative).
2. Validate both 'offset' and 'at'.
Signed-off-by: Amir Vadai <amir@xxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
net/sched/act_pedit.c | 24 ++++++++++++++++++++----
1 file changed, 20 insertions(+), 4 deletions(-)
--- a/net/sched/act_pedit.c
+++ b/net/sched/act_pedit.c
@@ -103,6 +103,17 @@ static void tcf_pedit_cleanup(struct tc_
kfree(keys);
}
+static bool offset_valid(struct sk_buff *skb, int offset)
+{
+ if (offset > 0 && offset > skb->len)
+ return false;
+
+ if (offset < 0 && -offset > skb_headroom(skb))
+ return false;
+
+ return true;
+}
+
static int tcf_pedit(struct sk_buff *skb, const struct tc_action *a,
struct tcf_result *res)
{
@@ -129,6 +140,11 @@ static int tcf_pedit(struct sk_buff *skb
if (tkey->offmask) {
char *d, _d;
+ if (!offset_valid(skb, off + tkey->at)) {
+ pr_info("tc filter pedit 'at' offset %d out of bounds\n",
+ off + tkey->at);
+ goto bad;
+ }
d = skb_header_pointer(skb, off + tkey->at, 1,
&_d);
if (!d)
@@ -141,10 +157,10 @@ static int tcf_pedit(struct sk_buff *skb
" offset must be on 32 bit boundaries\n");
goto bad;
}
- if (offset > 0 && offset > skb->len) {
- pr_info("tc filter pedit"
- " offset %d can't exceed pkt length %d\n",
- offset, skb->len);
+
+ if (!offset_valid(skb, off + offset)) {
+ pr_info("tc filter pedit offset %d out of bounds\n",
+ offset);
goto bad;
}