From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 87AEA478E2B; Tue, 16 Jun 2026 17:16:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781630194; cv=none; b=hM35IZwrVVLnVKPwBCGdZv10S3YwJVvoPmJeS/biAPux22xnQuUCW1zGRwUk+0UR9cEpLtumNpT1GR2UAur6scnOQsx2QNauGCCs+Jzr388IHp5Sms7fFAOz9FnW96rePyYNfWLDN3viII/Jbxzz+nurFzDW+v7LbEYpPXHe7rg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781630194; c=relaxed/simple; bh=K/WT5SLtgJjVRNCgemDbXS4sjJqt37RIiNmUkkqJlrU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=GaLhycji2sjp0KmzNdmDqKtdoAByUr5pYt2jSEw4bXvDQ4t31RjQC0SIy9ebtTmxz4jS86dGH3wg/J+WZK+jnEvPUpnwT+lQGFD2xsc7W77D9jHInNE0owK85hjq/8h7gUvglUvhc3ZlR37VH337ftxGiiEL890ajoD4exNmTPs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=pk5qOi+I; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="pk5qOi+I" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B40211F00A3A; Tue, 16 Jun 2026 17:16:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1781630188; bh=CAnLZT4awvxgzGC9tgqw+rHG4Q7OytV3r7zOh3j1i9U=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=pk5qOi+I+Gg40KNn7/E55AC1HPEJYKqiq9lIA/TylPNooVOQ8IcbIyqD2gxDjufKC 3ifBa3VbLSvdROXnzBiXaqcC6jrIhpqjZPm5oBO3O70EqP3f5EC25IHhC1kHvuU4f5 juUJmqY9NpEfptWTnEh4TYAQRk0Uh99Lpj6PSvbI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Florian Westphal , Davide Ornaghi , Pablo Neira Ayuso , Sasha Levin Subject: [PATCH 6.6 427/452] netfilter: nft_fib: fix stale stack leak via the OIFNAME register Date: Tue, 16 Jun 2026 20:30:54 +0530 Message-ID: <20260616145139.121131858@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260616145117.796205997@linuxfoundation.org> References: <20260616145117.796205997@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Davide Ornaghi [ Upstream commit ab185e0c4fb82dfba6fb86f8271e06f931d9c64c ] For NFT_FIB_RESULT_OIFNAME the destination register is declared with len = IFNAMSIZ (four 32-bit registers), but on the lookup-fail, RTN_LOCAL and oif-mismatch paths nft_fib{4,6}_eval() only writes one register via "*dest = 0". The remaining three registers are left as whatever was on the stack in nft_do_chain()'s struct nft_regs, and a downstream expression that loads the register span can leak that uninitialised kernel stack to userspace. The NFTA_FIB_F_PRESENT existence check has the same shape: it is only meaningful for NFT_FIB_RESULT_OIF, yet it was accepted for any result type while the eval stores a single byte via nft_reg_store8(), leaving the rest of the declared span stale. Fix both: - replace the bare "*dest = 0" in the eval with nft_fib_store_result(), which strscpy_pad()s the whole IFNAMSIZ for OIFNAME (and is already used on the other early-return path), and - restrict NFTA_FIB_F_PRESENT to NFT_FIB_RESULT_OIF and declare its destination as a single u8, so the marked span matches the one byte the eval writes. Fixes: f6d0cbcf09c5 ("netfilter: nf_tables: add fib expression") Suggested-by: Florian Westphal Cc: stable@vger.kernel.org Signed-off-by: Davide Ornaghi Signed-off-by: Pablo Neira Ayuso [ kept the tree's existing `ip6_route_lookup`/`rt6_info` machinery (missing `fib6_lookup` refactor) and changed only `*dest = 0;` to `nft_fib_store_result(dest, priv, NULL)` ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- net/ipv4/netfilter/nft_fib_ipv4.c | 2 +- net/ipv6/netfilter/nft_fib_ipv6.c | 2 +- net/netfilter/nft_fib.c | 6 ++++++ 3 files changed, 8 insertions(+), 2 deletions(-) --- a/net/ipv4/netfilter/nft_fib_ipv4.c +++ b/net/ipv4/netfilter/nft_fib_ipv4.c @@ -122,7 +122,7 @@ void nft_fib4_eval(const struct nft_expr fl4.saddr = get_saddr(iph->daddr); } - *dest = 0; + nft_fib_store_result(dest, priv, NULL); if (fib_lookup(nft_net(pkt), &fl4, &res, FIB_LOOKUP_IGNORE_LINKSTATE)) return; --- a/net/ipv6/netfilter/nft_fib_ipv6.c +++ b/net/ipv6/netfilter/nft_fib_ipv6.c @@ -193,7 +193,7 @@ void nft_fib6_eval(const struct nft_expr } } - *dest = 0; + nft_fib_store_result(dest, priv, NULL); rt = (void *)ip6_route_lookup(nft_net(pkt), &fl6, pkt->skb, lookup_flags); if (rt->dst.error) --- a/net/netfilter/nft_fib.c +++ b/net/netfilter/nft_fib.c @@ -107,6 +107,12 @@ int nft_fib_init(const struct nft_ctx *c return -EINVAL; } + if (priv->flags & NFTA_FIB_F_PRESENT) { + if (priv->result != NFT_FIB_RESULT_OIF) + return -EINVAL; + len = sizeof(u8); + } + err = nft_parse_register_store(ctx, tb[NFTA_FIB_DREG], &priv->dreg, NULL, NFT_DATA_VALUE, len); if (err < 0)