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 99C9D54739 for ; Mon, 15 Jun 2026 03:50:00 +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=1781495401; cv=none; b=YdQFptTAuCVzN5O3Mw4hupTpqdfkOqy6RZ4t+WpeaJ2Zc0RattRj5BZiMjdBvDmrnmIRVS9rzhPJH0aFSpfJXRT0Cj55WR8SKWv9PUuyStWL03EDmPPRtLA73ypXvTmfcjjlGW0cm7PoJMOp6fRIinZ/VrHXrNwJHMqb8X7dnug= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781495401; c=relaxed/simple; bh=0fjZn/2T1fq/E2Teo9Ge1KJaw3ciKq6CzS7VpYO6zvw=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=g1zpAP2FbKS32llseKKSyzlHj+wOv/vmxmaBBM+S/SNzOQV+dhHPV6MefGulB6mNbLCFZAD4n4x7vO3rJf4h4++Ot6iZFuSvx7ETZpnx8PIpKybQ7m1N/aWIe1OfkUsGx9czFezgiciZP1Usy6AWxtYa95bBReXGYOhpkpqRKqM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=YwTYbEjL; 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="YwTYbEjL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8E67C1F000E9; Mon, 15 Jun 2026 03:49:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1781495400; bh=HMH14TYtDVRSjrxdHVnAyIEFF016D6Hwm0uM/wjuwZg=; h=Subject:To:Cc:From:Date; b=YwTYbEjL78FNgpDlNc96sh3pt4VQfLuPFOjsqxhTQdbk4TKfC+IQ8lSTKm2zn3IXp fCz5pH3zz4hjjxj+ix9/ltKoCe4lLBgKP/4XyMFCKgzvMwKtsgSb4YPERBq6R114+I pxp1twouZtcEzp12IZ28H+TG0EkIrAYfjawuNnh8= Subject: FAILED: patch "[PATCH] netfilter: nft_fib: fix stale stack leak via the OIFNAME" failed to apply to 5.15-stable tree To: d.ornaghi97@gmail.com,fw@strlen.de,pablo@netfilter.org Cc: From: Date: Mon, 15 Jun 2026 05:48:44 +0200 Message-ID: <2026061544-juicy-dispatch-14c9@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x ab185e0c4fb82dfba6fb86f8271e06f931d9c64c # git commit -s git send-email --to '' --in-reply-to '2026061544-juicy-dispatch-14c9@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From ab185e0c4fb82dfba6fb86f8271e06f931d9c64c Mon Sep 17 00:00:00 2001 From: Davide Ornaghi Date: Wed, 10 Jun 2026 12:39:12 +0200 Subject: [PATCH] netfilter: nft_fib: fix stale stack leak via the OIFNAME register 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 diff --git a/net/ipv4/netfilter/nft_fib_ipv4.c b/net/ipv4/netfilter/nft_fib_ipv4.c index 9d0c6d75109b..177d738825b4 100644 --- a/net/ipv4/netfilter/nft_fib_ipv4.c +++ b/net/ipv4/netfilter/nft_fib_ipv4.c @@ -128,7 +128,7 @@ void nft_fib4_eval(const struct nft_expr *expr, struct nft_regs *regs, 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; diff --git a/net/ipv6/netfilter/nft_fib_ipv6.c b/net/ipv6/netfilter/nft_fib_ipv6.c index 2dbe44715df3..b9ad7cac1417 100644 --- a/net/ipv6/netfilter/nft_fib_ipv6.c +++ b/net/ipv6/netfilter/nft_fib_ipv6.c @@ -239,7 +239,7 @@ void nft_fib6_eval(const struct nft_expr *expr, struct nft_regs *regs, lookup_flags = nft_fib6_flowi_init(&fl6, priv, pkt, oif, iph); - *dest = 0; + nft_fib_store_result(dest, priv, NULL); ret = nft_fib6_lookup(nft_net(pkt), &fl6, &res, lookup_flags); if (ret || res.fib6_flags & (RTF_REJECT | RTF_ANYCAST | RTF_LOCAL)) return; diff --git a/net/netfilter/nft_fib.c b/net/netfilter/nft_fib.c index 327a5f33659c..a1632e308f18 100644 --- a/net/netfilter/nft_fib.c +++ b/net/netfilter/nft_fib.c @@ -107,6 +107,12 @@ int nft_fib_init(const struct nft_ctx *ctx, const struct nft_expr *expr, 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)