From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 463B5C43334 for ; Fri, 3 Jun 2022 18:01:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346024AbiFCSBG (ORCPT ); Fri, 3 Jun 2022 14:01:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47798 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346264AbiFCSAI (ORCPT ); Fri, 3 Jun 2022 14:00:08 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AA02053716; Fri, 3 Jun 2022 10:55:56 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 37BB2B8241D; Fri, 3 Jun 2022 17:55:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6E8CDC385A9; Fri, 3 Jun 2022 17:55:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1654278953; bh=iD1LTKLrroJIGGWbrPOT5G7rn4yVI1cE+hIePOwluT0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=j4kOEeuC2YPf8adyd7pLtTuZxI4npRXQWyDHv9a0WtK4Ufc1S5cpLOTTZRuCJj9k7 xaT1vjcKoPAvP9A3EGDuj22uqRxa/l81j9KEzbTq63XVeBcW3UxN/U53cTPcoST89X WtXymwK1gIuD27BITOEkV2rDUPeFQzXtEyy4c3wc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Andrii Nakryiko , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau Subject: [PATCH 5.17 70/75] bpf: Fix combination of jit blinding and pointers to bpf subprogs. Date: Fri, 3 Jun 2022 19:43:54 +0200 Message-Id: <20220603173823.714252183@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220603173821.749019262@linuxfoundation.org> References: <20220603173821.749019262@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Alexei Starovoitov commit 4b6313cf99b0d51b49aeaea98ec76ca8161ecb80 upstream. The combination of jit blinding and pointers to bpf subprogs causes: [ 36.989548] BUG: unable to handle page fault for address: 0000000100000001 [ 36.990342] #PF: supervisor instruction fetch in kernel mode [ 36.990968] #PF: error_code(0x0010) - not-present page [ 36.994859] RIP: 0010:0x100000001 [ 36.995209] Code: Unable to access opcode bytes at RIP 0xffffffd7. [ 37.004091] Call Trace: [ 37.004351] [ 37.004576] ? bpf_loop+0x4d/0x70 [ 37.004932] ? bpf_prog_3899083f75e4c5de_F+0xe3/0x13b The jit blinding logic didn't recognize that ld_imm64 with an address of bpf subprogram is a special instruction and proceeded to randomize it. By itself it wouldn't have been an issue, but jit_subprogs() logic relies on two step process to JIT all subprogs and then JIT them again when addresses of all subprogs are known. Blinding process in the first JIT phase caused second JIT to miss adjustment of special ld_imm64. Fix this issue by ignoring special ld_imm64 instructions that don't have user controlled constants and shouldn't be blinded. Fixes: 69c087ba6225 ("bpf: Add bpf_for_each_map_elem() helper") Reported-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Acked-by: Martin KaFai Lau Link: https://lore.kernel.org/bpf/20220513011025.13344-1-alexei.starovoitov@gmail.com Signed-off-by: Greg Kroah-Hartman --- kernel/bpf/core.c | 10 ++++++++++ 1 file changed, 10 insertions(+) --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -1157,6 +1157,16 @@ struct bpf_prog *bpf_jit_blind_constants insn = clone->insnsi; for (i = 0; i < insn_cnt; i++, insn++) { + if (bpf_pseudo_func(insn)) { + /* ld_imm64 with an address of bpf subprog is not + * a user controlled constant. Don't randomize it, + * since it will conflict with jit_subprogs() logic. + */ + insn++; + i++; + continue; + } + /* We temporarily need to hold the original ld64 insn * so that we can still access the first part in the * second blinding run.