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 2E9CA3D75C7; Wed, 20 May 2026 17:39:19 +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=1779298760; cv=none; b=Fz2F9vcWuKsbJ1LJAJCyw/m5IPmVhgMSrqvMiJPq0Ru6oJWpXYpzp+nfdNixzvyrB/AtHjiVNAUSIMNoH+h9jJKYyGZ8bmYNK4oZHGJcFLG+C+mlV0Dp0dS+5oN5xtcc2R8hUOi/NHjTgp4zhy2xyK8/z2I42ucZH1/8uKJ8QN0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779298760; c=relaxed/simple; bh=qXJ2DMtLVvRnhaiCQmZMbsVLg6Y8z2FyFk1cIC6dHlc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=QCSGGC0dk5kyCNw93h/f4Ol1FjQN5Zvv+NvUNskWUgg6ss8r9HejKU/coEelckFe9+iLOZaAqmYzisNZ3wq9+6UoXladyg4cdyf6FVn6k9UNd2StMpe56l2DoZYmkHZulbgj0/BV0u202t660ymoQfCXqPMhl/z125wt/cd1ses= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=DD+pbkAD; 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="DD+pbkAD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 94AC11F000E9; Wed, 20 May 2026 17:39:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1779298759; bh=x2zGGaTRoYAXYMO4q9XJ7Er0Ay1PaGrUops47JeC/GQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=DD+pbkAD5JNhXLs7d7hn0lDyXN7iaPbuHzsaU8SbgeVnS2h0MlFZyMp9bHX4Ob50d zcZftYzSNHEzdblabBpKzNWILBMIp1+PJwPbS4dsnjQPcNnVIOHxOGq6MpifK5g7H6 /4Y/J6DjdCFZfAvlCdnM5nmKVQFEVwFHyAdRmdZA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Daniel Borkmann , Alexei Starovoitov , Sasha Levin Subject: [PATCH 6.18 491/957] bpf: Fix precedence bug in convert_bpf_ld_abs alignment check Date: Wed, 20 May 2026 18:16:14 +0200 Message-ID: <20260520162145.174475329@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260520162134.554764788@linuxfoundation.org> References: <20260520162134.554764788@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Daniel Borkmann [ Upstream commit e5f635edd393aeaa7cad9e42831d397e6e2e1eed ] Fix an operator precedence issue in convert_bpf_ld_abs() where the expression offset + ip_align % size evaluates as offset + (ip_align % size) due to % having higher precedence than +. That latter evaluation does not make any sense. The intended check is (offset + ip_align) % size == 0 to verify that the packet load offset is properly aligned for direct access. With NET_IP_ALIGN == 2, the bug causes the inline fast-path for direct packet loads to almost never be taken on !CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS platforms. This forces nearly all cBPF BPF_LD_ABS packet loads through the bpf_skb_load_helper slow path on the affected archs. Fixes: e0cea7ce988c ("bpf: implement ld_abs/ld_ind in native bpf") Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/r/20260416122719.661033-1-daniel@iogearbox.net Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin --- net/core/filter.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/core/filter.c b/net/core/filter.c index 7fc01474c3781..ae6d0453cf123 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -508,7 +508,7 @@ static bool convert_bpf_ld_abs(struct sock_filter *fp, struct bpf_insn **insnp) ((unaligned_ok && offset >= 0) || (!unaligned_ok && offset >= 0 && offset + ip_align >= 0 && - offset + ip_align % size == 0))) { + (offset + ip_align) % size == 0))) { bool ldx_off_ok = offset <= S16_MAX; *insn++ = BPF_MOV64_REG(BPF_REG_TMP, BPF_REG_H); -- 2.53.0