A verdict of NF_STOLEN after NF_QUEUE will cause an incorrect return value
and a potential kernel panic via double free of skb's
This was broken by commit 7034b566a4e7 ("netfilter: fix nf_queue handling")
and subsequently fixed in v4.10 by commit c63cbc460419 ("netfilter:
use switch() to handle verdict cases from nf_hook_slow()"). However that
commit cannot be cleanly cherry-picked to v4.9
Signed-off-by: Debabrata Banerjee <dbanerje@xxxxxxxxxx>
---
This fix is only needed for v4.9 stable since v4.10+ does not have the
issue
---
net/netfilter/core.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/net/netfilter/core.c b/net/netfilter/core.c
index 004af030ef1a..d869ea50623e 100644
--- a/net/netfilter/core.c
+++ b/net/netfilter/core.c
@@ -364,6 +364,11 @@ int nf_hook_slow(struct sk_buff *skb, struct nf_hook_state *state)
ret = nf_queue(skb, state, &entry, verdict);
if (ret == 1 && entry)
goto next_hook;
+ } else {
+ /* Implicit handling for NF_STOLEN, as well as any other
+ * non conventional verdicts.
+ */
+ ret = 0;
}
return ret;
}
--
2.15.1