From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=209.85.221.172 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792707450; b=O85WDND6MUd316GFIp1Za2HtPgijt186sH60x8P4Bmy0e9ySmiTI03ZH6livK1nGesmY 8XY+9vTnwSKNlHXY3zCsmi8smDigCTFaxHPhyuytQPrAW1yqJ0GBsV86/cRFv67eDUwJx bAyU2KjMqZlTsOJRnNlswSbw/uHNkyiy/iGXIPujMEmScaMIFqJHIEydmbjZLHLHjJEUG kIw46wB/xhP335P30Q2x6z0tRaVOeysRir0PsJyXvkO9jBXPyIeYrjC6fJFwjr+L5LzkH T/3ar3mK0Pn3QwLLmwbpcDDEqMi49gbf/1WOMKR5xJ0qRpPjeZqNAnJGpv0w+Q+q83A== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792707450; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Forwarded-Encrypted:X-Gm-Message-State:X-Gm-Gg:X-Received:Received: From:To:Cc:Subject:Date:Message-ID:X-Mailer:In-Reply-To:References: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=lomsEIzafjLVZya86Pfl4U9atLbvZi9DCA+wyh807aw=; b=P0TpeUWCEepNlDTMlJP0fmTBoD15Z2lxOJqGFGrpvs0jpeMBPuLx5re3D0EbAQYtGoBB sSiHg3hhVJ/Sq7HfgPfFDgaLs50b8vQLa6QcmPWW94RvxV/gZE0AMHj3PohYdjGYWbG9y T/P+ZAPFqQCTUrKLlkfgu32mTuVazfZgTOt4OLBzkIlY3MaEqwPJwP8dnfFL0GJ8GYIb5 qwaZLToBbZ3jfYJf8DbqSh24ARkV+/YkAFN2qAP9B+AmVj1c8mDERCZZHgWErItsVxLQc hHQ7pr83uWFu6W0gcp/u+bZE3WnQXkHRFforuKDn4HxSRptphlw21fxGA4m4Aj+cAXQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20251104 header.b=UGp6xEo4; arc=none smtp.remote-ip=209.85.221.172 Received: from mail-vk1-f172.google.com (mail-vk1-f172.google.com [209.85.221.172]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AAA40606A319 for ; Thu, 22 Oct 2026 22:17:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org AAA40606A319 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20251104 header.b=UGp6xEo4 Received: by mail-vk1-f172.google.com with SMTP id 71dfb90a1353d-5eafaeb8684so126760e0c.3 for ; Thu, 22 Oct 2026 15:17:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1792707448; x=1793312248; darn=vger.kernel.org; h=content-transfer-encoding:content-type:mime-version:references :in-reply-to:message-id:date:subject:cc:to:from:from:to:cc:subject :date:message-id:reply-to:content-type; bh=lomsEIzafjLVZya86Pfl4U9atLbvZi9DCA+wyh807aw=; b=UGp6xEo46X7hYGvsFsa/zX4GnG5h62cMJTqHLj8i8AKrS9J3hbUQrjgzFhQipOB5s0 hCxwO0BSTsvVFwyx5H+uP2v2FKo5IInzNPnr0u0dUnEcQ3YPFbSzJVc4eXZAJG+j8NLb tSPUe8oEQSj9qbppiYXKURYXMHrj3PZbj8ekQuBAzgtsgoX6EzPtpixHmmCuj75hZX9C DaIeyR/G+EZyir/jT5XvHZ3HMlKd1Ub3kwmD/yklUnqz7a5LrPCbKekEAN7kN85d3mbh diyanZfKbfsdUp25hWiQMSXGYxyDEmbSflG/8REV/USoftVz+HLZcUtcJ/HGlMUXVlRk GoMQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1792707448; x=1793312248; h=content-transfer-encoding:content-type:mime-version:references :in-reply-to:message-id:date:subject:cc:to:from:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=lomsEIzafjLVZya86Pfl4U9atLbvZi9DCA+wyh807aw=; b=zn2vbb73X2iTF7DPlEP9MxHgsQlqDRFPT0prY98RRgrT1G9NsYAvSRSx0+JfNKHgXG Lm9llPXkCkRqqwtTa0CiilIwpz3F48XIi6LW1PKP48hGMw5VHr3eeczhAidnXPQNulXo GqmlV5p6BKFQq1Lo0TlPVa0Xb3AUQjUi+ufgZ2GctZKbicJUmoQfY7Omvis98dIx1EPR SosB036ANKHexVkRkxcXg//zk4x8vqlwqMrFbitaSp16Gn1LDERO8GxWZVr406ZdRmi6 cQPN39NCT2qlXoAcD7/1hk5PPoJhRwz6U/HG/qkupaj1b9kLPJfjGHEUgtpwI+mR814n pltg== X-Forwarded-Encrypted: i=1; AKwUvBzJcsBgi2tV8mGcPkAIFx2ibb59IljRA0utuqEh1mBK0zR55X05+cgRQjWCMsZMur1r3aWqmbL8UGHFTpc=@vger.kernel.org X-Gm-Message-State: AFq9FYIkSQQ7mJeiBo9K3xJb8pkKkMIoB5yPtmcpG4Q8fNNzX0v1LxrA D+k39Kn07R8nWhprD/MWH0EYK7mV/ztf2K2EGANzPi44f82xbfyVG5qU X-Gm-Gg: AYBFou0pdZ9jlsGgOWA7m1GQawyaSBn6YIGRzjDsdi9fGskHTEzIfb2tND0mZR8nhPr Pr/0Beuv5HzFYKQGf2Y6HbQEyDGwM9ChA3lJbBMo3ehaaBfKiJ2EGUW+2uvImNRmg3v6O5JMAHq Oix6ygiRUrvc+HxCfovOLM3fXJZF8C63+kLugxAXDH7XlRT+J6Kzt0SQp5ITpLBCnGXI3u+51qM r4XhYdv5NJ+FnHfU2q2ZU34sOFr6bR8LTAR4B8quwdlhSbOV5lksgrfRFYZ2pMiao7Gg9F9s3ab Qne89QIya04Jy8K60Ugt6o2CysqWtX4OXdmsry9RLqQ547eOTic8kU6ZoYmX7jeOD8S7sXsyP15 6Rv7pu2QQ10YxQh94kc6Q3zlsbp8abrHlYbGYZAjYXbitVxm9ikapS5fxw5ARSJFvQhOhlujBcS yzt+2mz0EhYT1khZfDz/9c5TXhPX1pS4NLhg9eAjFmbJl/GeGRbmbrXtICsOkdbqskO80OiQaAH VwShAEhYhNEmmnQaoxfj+JQ7V9rTYjaDF1/kuxMSy1+ur2f6Q== X-Received: by 2002:a05:6122:3d08:b0:5ea:c084:6f19 with SMTP id 71dfb90a1353d-5ec14a789ebmr114559e0c.12.1792707448568; Thu, 22 Oct 2026 15:17:28 -0700 (PDT) Received: from unix.. ([181.229.23.179]) by smtp.gmail.com with ESMTPSA id 71dfb90a1353d-5ec13f2cfe0sm456271e0c.14.2026.10.22.15.17.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Oct 2026 15:17:28 -0700 (PDT) From: =?UTF-8?q?Iv=C3=A1n=20Ezequiel=20Rodriguez?= To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org Cc: "H . Peter Anvin" , Shuah Khan , Christian Brauner , Rick Edgecombe , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, =?UTF-8?q?Iv=C3=A1n=20Ezequiel=20Rodriguez?= Subject: [PATCH v2 0/2] x86/shstk: don't leak a shadow stack when clone TLS fails Date: Thu, 22 Oct 2026 19:17:19 -0300 Message-ID: <20261022221722.619233-1-ivanrwcm25@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20261015023147.519257-1-ivanrwcm25@gmail.com> References: <20261015023147.519257-1-ivanrwcm25@gmail.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit copy_thread() maps a shadow stack and set_new_tls() can still fail. That error goes to bad_fork_cleanup_io and skips exit_thread(). bad_fork_cleanup_thread calls exit_thread() only after copy_thread() has returned 0. commit 748c90c69336 ("x86/shstk: Remove useless clone error handling") removed the shstk_free() on the set_new_tls() failure. Restoring it only there puts back the single free. The allocation-error return still aliases the parent, and the exit_thread() path is left alone, so the double unmap that commit avoided does not come back. The selftest uses kselftest.h / KTAP. Feature and clone3 availability skips run before ksft_set_plan(). Missing /proc/self/smaps is SKIP. Read errors, truncated smaps lines, and a VMA range without VmFlags are FAIL. A valid-TLS clone3 must succeed before EPERM on a bad TLS counts as the leak path; ENOSYS/EPERM/EACCES SKIP that control. Regression (CONFIG_X86_USER_SHADOW_STACK=y, host and one-vCPU KVM -cpu host,migratable=off): Scenario Without fix With fix 16 bad-TLS clone3 +16 ss VMAs +0 ss VMAs Parent shadow stack kept + call/ret OK kept + call/ret OK KTAP 2/3 (test 3 fail) 3/3 pass Changes in v2: - Nest the TLS error check under CLONE_SETTLS, as suggested by Rick Edgecombe. - Use a dedicated shadow-stack cleanup label. - Return zero explicitly on the successful path. - Remove the redundant cleanup comment. - Selftest: rewrite on kselftest.h / KTAP (plan 3). Fix RDSSPQ comment; align get_ssp() with test_shadow_stack; SKIP only ENOSYS/EPERM/EACCES on the valid-TLS control; FAIL on truncated or incomplete smaps records that would under-count ss VMAs. Link: https://lore.kernel.org/lkml/20261015023147.519257-1-ivanrwcm25@gmail.com/ Iván Ezequiel Rodriguez (2): x86/shstk: free shadow stack when copy_thread() fails selftests/x86: shadow stack must survive a bad TLS arch/x86/kernel/process.c | 13 +- tools/testing/selftests/x86/Makefile | 3 +- tools/testing/selftests/x86/shstk_clone_tls.c | 334 ++++++++++++++++++ 3 files changed, 346 insertions(+), 4 deletions(-) create mode 100644 tools/testing/selftests/x86/shstk_clone_tls.c -- 2.43.0