4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Debabrata Banerjee dbanerje@akamai.com
[This fix is only needed for v4.9 stable since v4.10+ does not have the issue]
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@akamai.com Acked-by: Pablo Neira Ayuso pablo@netfilter.org
--- net/netfilter/core.c | 5 +++++ 1 file changed, 5 insertions(+)
--- a/net/netfilter/core.c +++ b/net/netfilter/core.c @@ -364,6 +364,11 @@ next_hook: 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; }