From 7b1d83da254be3bf054965c8f3b1ad976f460ae5 Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Wed, 27 Nov 2024 12:46:54 +0100 Subject: netfilter: nft_inner: incorrect percpu area handling under softirq Softirq can interrupt ongoing packet from process context that is walking over the percpu area that contains inner header offsets. Disable bh and perform three checks before restoring the percpu inner header offsets to validate that the percpu area is valid for this skbuff: 1) If the NFT_PKTINFO_INNER_FULL flag is set on, then this skbuff has already been parsed before for inner header fetching to register. 2) Validate that the percpu area refers to this skbuff using the skbuff pointer as a cookie. If there is a cookie mismatch, then this skbuff needs to be parsed again. 3) Finally, validate if the percpu area refers to this tunnel type. Only after these three checks the percpu area is restored to a on-stack copy and bh is enabled again. After inner header fetching, the on-stack copy is stored back to the percpu area. Fixes: 3a07327d10a0 ("netfilter: nft_inner: support for inner tunnel header matching") Reported-by: syzbot+84d0441b9860f0d63285@syzkaller.appspotmail.com Signed-off-by: Pablo Neira Ayuso --- include/net/netfilter/nf_tables_core.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include') diff --git a/include/net/netfilter/nf_tables_core.h b/include/net/netfilter/nf_tables_core.h index ff27cb2e1662..03b6165756fc 100644 --- a/include/net/netfilter/nf_tables_core.h +++ b/include/net/netfilter/nf_tables_core.h @@ -161,6 +161,7 @@ enum { }; struct nft_inner_tun_ctx { + unsigned long cookie; u16 type; u16 inner_tunoff; u16 inner_lloff; -- cgit v1.2.3