netfilter: nfnetlink_osf: fix possible bogus match in nf_osf_find()

[ Upstream commit 559c36c5a8d730c49ef805a72b213d3bba155cc8 ]

nf_osf_find() incorrectly returns true on mismatch, this leads to
copying uninitialized memory area in nft_osf which can be used to leak
stale kernel stack data to userspace.

Fixes: 22c7652cdaa8 ("netfilter: nft_osf: Add version option support")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/netfilter/nfnetlink_osf.c b/net/netfilter/nfnetlink_osf.c
index 0fa2e20..ee6840b 100644 (file)
--- a/net/netfilter/nfnetlink_osf.c
+++ b/net/netfilter/nfnetlink_osf.c
@@ -269,6 +269,7 @@ bool nf_osf_find(const struct sk_buff *skb,
        struct nf_osf_hdr_ctx ctx;
        const struct tcphdr *tcp;
        struct tcphdr _tcph;
+       bool found = false;
 
        memset(&ctx, 0, sizeof(ctx));
 
@@ -283,10 +284,11 @@ bool nf_osf_find(const struct sk_buff *skb,
 
                data->genre = f->genre;
                data->version = f->version;
+               found = true;
                break;
        }
 
-       return true;
+       return found;
 }
 EXPORT_SYMBOL_GPL(nf_osf_find);