[PATCH 5.15 068/148] netfilter: nfnetlink_osf: fix possible bogus match in nf_osf_find()

Greg Kroah-Hartman
2022-09-26T11:16:33Z

From: Pablo Neira Ayuso <pablo@netfilter.org>

[ 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>
---
net/netfilter/nfnetlink_osf.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/nfnetlink_osf.c b/net/netfilter/nfnetlink_osf.c
index 0fa2e2030427..ee6840bd5933 100644
--- 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);

--
2.35.1