From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 F073F5101A; Mon, 11 Dec 2023 18:27:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="2A9w0gxN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 73D92C433C8; Mon, 11 Dec 2023 18:27:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1702319234; bh=j0USQOdhPCKAOQUwxXeIxVfUzqbYPexJenADJVtTG88=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2A9w0gxNgLrFoOuyPxX2SHPm8tF91CbEZ7sRDaan3C6N4p6swZsaB3mrGBBqaBzxm oEjCtW5H3V8NukbOdGi1B+BGcVTsshKgYx87EQmx9DKfc0gHfYdFxbz+qbgpbizGpg TKn6+vV6lwGQYyp6spLJY9uQ0F6e9Qs5biGhVIYg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yonghong Song , Andrii Nakryiko , Sasha Levin Subject: [PATCH 6.6 030/244] bpf: Fix a verifier bug due to incorrect branch offset comparison with cpu=v4 Date: Mon, 11 Dec 2023 19:18:43 +0100 Message-ID: <20231211182047.150038062@linuxfoundation.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231211182045.784881756@linuxfoundation.org> References: <20231211182045.784881756@linuxfoundation.org> User-Agent: quilt/0.67 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 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yonghong Song [ Upstream commit dfce9cb3140592b886838e06f3e0c25fea2a9cae ] Bpf cpu=v4 support is introduced in [1] and Commit 4cd58e9af8b9 ("bpf: Support new 32bit offset jmp instruction") added support for new 32bit offset jmp instruction. Unfortunately, in function bpf_adj_delta_to_off(), for new branch insn with 32bit offset, the offset (plus/minor a small delta) compares to 16-bit offset bound [S16_MIN, S16_MAX], which caused the following verification failure: $ ./test_progs-cpuv4 -t verif_scale_pyperf180 ... insn 10 cannot be patched due to 16-bit range ... libbpf: failed to load object 'pyperf180.bpf.o' scale_test:FAIL:expect_success unexpected error: -12 (errno 12) #405 verif_scale_pyperf180:FAIL Note that due to recent llvm18 development, the patch [2] (already applied in bpf-next) needs to be applied to bpf tree for testing purpose. The fix is rather simple. For 32bit offset branch insn, the adjusted offset compares to [S32_MIN, S32_MAX] and then verification succeeded. [1] https://lore.kernel.org/all/20230728011143.3710005-1-yonghong.song@linux.dev [2] https://lore.kernel.org/bpf/20231110193644.3130906-1-yonghong.song@linux.dev Fixes: 4cd58e9af8b9 ("bpf: Support new 32bit offset jmp instruction") Signed-off-by: Yonghong Song Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20231201024640.3417057-1-yonghong.song@linux.dev Signed-off-by: Sasha Levin --- kernel/bpf/core.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 64fcd81ad3da4..5d1efe5200ba3 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -371,14 +371,18 @@ static int bpf_adj_delta_to_imm(struct bpf_insn *insn, u32 pos, s32 end_old, static int bpf_adj_delta_to_off(struct bpf_insn *insn, u32 pos, s32 end_old, s32 end_new, s32 curr, const bool probe_pass) { - const s32 off_min = S16_MIN, off_max = S16_MAX; + s64 off_min, off_max, off; s32 delta = end_new - end_old; - s32 off; - if (insn->code == (BPF_JMP32 | BPF_JA)) + if (insn->code == (BPF_JMP32 | BPF_JA)) { off = insn->imm; - else + off_min = S32_MIN; + off_max = S32_MAX; + } else { off = insn->off; + off_min = S16_MIN; + off_max = S16_MAX; + } if (curr < pos && curr + off + 1 >= end_old) off += delta; -- 2.42.0