From patchwork Wed Sep 11 04:40:22 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yonghong Song X-Patchwork-Id: 13799674 X-Patchwork-Delegate: bpf@iogearbox.net Received: from 69-171-232-180.mail-mxout.facebook.com (69-171-232-180.mail-mxout.facebook.com [69.171.232.180]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6128640862 for ; Wed, 11 Sep 2024 04:40:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=69.171.232.180 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726029637; cv=none; b=tg2Gj/boKFYw/zrtKatCKGeDvfPSu9z8Z0FxVxBcRk5BrVsDZZMFT9uyuih30S/5Z8l//FVSkrfShyR37rkkZVLmGxIcb73/UQ5AANYLb7xNtURcZr9kml2F8jjg8+z2lo6gDan7bbYJuufvXIZTOwR1rwIH75auldaEcy0CTMM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726029637; c=relaxed/simple; bh=R/FLHw0BdYsh5xBYKCad7p6buEuf7UZX1DMA7VuoYqQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=I36ghz5Qw5+s9cKxB7GyCJzLssIpmsKSeyHbS486w+IlaRyHb9mbIPEPudq8pPlWGeUyra1kJ7plc77S4fJCjS1GVGDRbSLUBoq81cn7NCbJuqjLpVmUJXEo8R6bAkPxc1kjNDhYkaHKfKZY4Aj6TSObIOQPQXaUJMZ/mfufm0Y= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.dev; spf=fail smtp.mailfrom=linux.dev; arc=none smtp.client-ip=69.171.232.180 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=linux.dev Received: by devbig309.ftw3.facebook.com (Postfix, from userid 128203) id EF6858D48E66; Tue, 10 Sep 2024 21:40:22 -0700 (PDT) From: Yonghong Song To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , kernel-team@fb.com, Martin KaFai Lau Subject: [PATCH bpf-next 2/2] selftests/bpf: Add a couple of tests for potential sdiv overflow Date: Tue, 10 Sep 2024 21:40:22 -0700 Message-ID: <20240911044022.2262427-1-yonghong.song@linux.dev> X-Mailer: git-send-email 2.43.5 In-Reply-To: <20240911044017.2261738-1-yonghong.song@linux.dev> References: <20240911044017.2261738-1-yonghong.song@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net Two subtests are added to exercise the patched code which handles LLONG_MIN/-1. The first subtest will cause kernel exception without previous kernel verifier change. The second subtest exercises part of the patched code logic and the end result is still correct. Translated asm codes are parts of correctness checking and those asm codes also make it easy to understand the patched code in verifier. Signed-off-by: Yonghong Song --- .../selftests/bpf/progs/verifier_sdiv.c | 69 +++++++++++++++++++ 1 file changed, 69 insertions(+) diff --git a/tools/testing/selftests/bpf/progs/verifier_sdiv.c b/tools/testing/selftests/bpf/progs/verifier_sdiv.c index 2a2271cf0294..c9c56008e534 100644 --- a/tools/testing/selftests/bpf/progs/verifier_sdiv.c +++ b/tools/testing/selftests/bpf/progs/verifier_sdiv.c @@ -1,6 +1,7 @@ // SPDX-License-Identifier: GPL-2.0 #include +#include #include #include "bpf_misc.h" @@ -770,6 +771,74 @@ __naked void smod64_zero_divisor(void) " ::: __clobber_all); } +SEC("socket") +__description("SDIV64, overflow, LLONG_MIN/-1") +__success __retval(1) +__arch_x86_64 +__xlated("0: r2 = 0x8000000000000000") +__xlated("2: r3 = -1") +__xlated("3: r4 = r2") +__xlated("4: if r3 != 0x0 goto pc+2") +__xlated("5: w2 ^= w2") +__xlated("6: goto pc+8") +__xlated("7: if r3 != 0xffffffff goto pc+6") +__xlated("8: r3 = 0x8000000000000000") +__xlated("10: if r2 != r3 goto pc+2") +__xlated("11: r3 = -1") +__xlated("12: goto pc+2") +__xlated("13: r3 = -1") +__xlated("14: r2 s/= r3") +__xlated("15: r0 = 0") +__xlated("16: if r2 != r4 goto pc+1") +__xlated("17: r0 = 1") +__xlated("18: exit") +__naked void sdiv64_overflow(void) +{ + asm volatile (" \ + r2 = %[llong_min] ll; \ + r3 = -1; \ + r4 = r2; \ + r2 s/= r3; \ + r0 = 0; \ + if r2 != r4 goto +1; \ + r0 = 1; \ + exit; \ +" : + : __imm_const(llong_min, LLONG_MIN) + : __clobber_all); +} + +SEC("socket") +__description("SDIV64, divisor -1") +__success __retval(-5) +__arch_x86_64 +__xlated("0: r2 = 5") +__xlated("1: r3 = -1") +__xlated("2: if r3 != 0x0 goto pc+2") +__xlated("3: w2 ^= w2") +__xlated("4: goto pc+8") +__xlated("5: if r3 != 0xffffffff goto pc+6") +__xlated("6: r3 = 0x8000000000000000") +__xlated("8: if r2 != r3 goto pc+2") +__xlated("9: r3 = -1") +__xlated("10: goto pc+2") +__xlated("11: r3 = -1") +__xlated("12: r2 s/= r3") +__xlated("13: r0 = r2") +__xlated("14: exit") +__naked void sdiv64_divisor_neg_1(void) +{ + asm volatile (" \ + r2 = 5; \ + r3 = -1; \ + r2 s/= r3; \ + r0 = r2; \ + exit; \ +" : + : __imm_const(llong_min, LLONG_MIN) + : __clobber_all); +} + #else SEC("socket")