From patchwork Fri Apr 12 02:59:01 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: David Gow X-Patchwork-Id: 788488 Received: from mail-yb1-f201.google.com (mail-yb1-f201.google.com [209.85.219.201]) (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 2039412B79 for ; Fri, 12 Apr 2024 02:59:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.219.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712890752; cv=none; b=CweWyMbAYGCecPX3g0ZSlO+W035cgZSUoYPMtb1YqZ8suGr0YXsnkMVLhmiPZQISMSIM6aH2VL5TBiRSATH82ZEj55g7Kxs36/W9ToQ14FhDz7h5tG+rhZXQpVWb3wxhi5bG+P0rTydnfbGHa8lsF6qIycTnACatFySTZZpxtjA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712890752; c=relaxed/simple; bh=hrqmwUE8fd1mN84iAge55zIcPoB9rx7z4jD8bJyRNiI=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=UBwqKQ9xTXr8+JlWdIYW5Ec9JSXR6k4WZz9RkPMtjJpEz+O4E8x5c3RkHcyhkELUG8P/K8YPj5UYZKFrA9bgt4hG8p3zJwUA23XZ9kgz0Q8Edsodf8+FdhwiVhiznPyYU/fXJf6RCeB7JjyxnYDCcrDrgKAFnjQuZ/q0lfcfnyw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--davidgow.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=h0d1LGDh; arc=none smtp.client-ip=209.85.219.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--davidgow.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="h0d1LGDh" Received: by mail-yb1-f201.google.com with SMTP id 3f1490d57ef6-dc74ac7d015so701360276.0 for ; Thu, 11 Apr 2024 19:59:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1712890750; x=1713495550; darn=vger.kernel.org; h=content-transfer-encoding:cc:to:from:subject:message-id :mime-version:date:from:to:cc:subject:date:message-id:reply-to; bh=N6pnMn18AJQJudL6vSBz3NgEO0nPvsr06Y+BmA4MJEs=; b=h0d1LGDhmNs6BqvmFFtJGU2b3eS79aRYAsEXsf6SLBXgLN4GetzYcra2fDoNG37bzR D686/wr8KX7bR2DT9NEj2GWcTySg64GvhUDVmSAuBqu+93q2E0MgfWsyzyPeqexCtD60 2liT5Ac8XQHEvj+R3vIRCc/qYdYGTLF58nFaIBJfN3v+moT1C6XKV/67P5ZZMocw5j1F G2tqtG9JzQtM3QvsRYeEI37TDTaPyAGvdVc7Fta5vrxxK8tLtmheSSD+j0cV6bJ6IRjK u1WWjUAzHwN7HB/PKiajkA6yhWi/nJYgNivfPH5YmKtnwLChUPSwHNy5Pu22rjhlMd6n wahg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1712890750; x=1713495550; h=content-transfer-encoding:cc:to:from:subject:message-id :mime-version:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=N6pnMn18AJQJudL6vSBz3NgEO0nPvsr06Y+BmA4MJEs=; b=sReVTie4sql9Bh9MVTVCUglF7xTb8q6S9w+2sJ3tFEjCBZbHCyoIdbVmMyJecbRWF7 kNUNjPLFg970+HwAQcYZ2DxGbN2UaSZFoZtNXnMjVB/2Hs+rmfEbdImbmJPDIaYGs0R2 IQ8bjAdZltiEyJ92QkECQaQQtCU9hEubTS0lB/V6DUU+N+WdEAwQx6lUqOXzSu8MRu3F JVJ83GYDNVJ0Gi7ltaPc/AvZv9concxDXB3KA6k73vPymOSnqHOAIyM8DQ5zQQfuLFAU 2USBtemV7OByeg+saqqPElj01LUv+mzWjV6tooUg1QN06RPtjRdaukjHyIOWcXJH1Ldp cGrw== X-Forwarded-Encrypted: i=1; AJvYcCVUVu8GXN9L6AP6vpArOUvr5ajB0oub3ZY7uep12PqYNeSkCoH3Qcq3VfavTGzklQDy3DcY8ySSgYlkmYHg+p5GSwHS96bvhtW8GV920Obp X-Gm-Message-State: AOJu0Yx9+OSUJQ3njq5c0DgbLQ0xGL0y33xcvDfTU7Vzc2JnaFfubhMV PR8j4+De3LOf8SlyAbSS/rj85wXf22CbpSFW4Gs5RkEEdxFM/2pkoMlwGrX7ij301n3zlmZJ+9e usPPK+XWpnA== X-Google-Smtp-Source: AGHT+IE+rLw4/WNq/lOIj0dIsfJTt0mD9xMOL8JlEywxbKsGGpQsGsw6MB0ICLRb0eflzl+Qlv9lKoV1g9u9Mw== X-Received: from slicestar.c.googlers.com ([fda3:e722:ac3:cc00:4f:4b78:c0a8:20a1]) (user=davidgow job=sendgmr) by 2002:a05:6902:1027:b0:dc6:dfd9:d423 with SMTP id x7-20020a056902102700b00dc6dfd9d423mr142022ybt.3.1712890750037; Thu, 11 Apr 2024 19:59:10 -0700 (PDT) Date: Fri, 12 Apr 2024 10:59:01 +0800 Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.44.0.683.g7961c838ac-goog Message-ID: <20240412025903.489470-1-davidgow@google.com> Subject: [PATCH] kunit: Fix race condition in try-catch completion From: David Gow To: Rae Moar , Kees Cook , " =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= " , Naresh Kamboju , Shuah Khan Cc: David Gow , Will Deacon , Dan Carpenter , Guenter Roeck , linux-kselftest@vger.kernel.org, kunit-dev@googlegroups.com, linux-kernel@vger.kernel.org, Brendan Higgins , Linux Kernel Functional Testing KUnit's try-catch infrastructure now uses vfork_done, which is always set to a valid completion when a kthread is created, but which is set to NULL once the thread terminates. This creates a race condition, where the kthread exits before we can wait on it. Keep a copy of vfork_done, which is taken before we wake_up_process() and so valid, and wait on that instead. Fixes: 4de2a8e4cca4 ("kunit: Handle test faults") Reported-by: Linux Kernel Functional Testing Closes: https://lore.kernel.org/lkml/20240410102710.35911-1-naresh.kamboju@linaro.org/ Tested-by: Linux Kernel Functional Testing Acked-by: Mickaël Salaün Signed-off-by: David Gow Tested-by: Miguel Ojeda --- lib/kunit/try-catch.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/lib/kunit/try-catch.c b/lib/kunit/try-catch.c index fa687278ccc9..6bbe0025b079 100644 --- a/lib/kunit/try-catch.c +++ b/lib/kunit/try-catch.c @@ -63,6 +63,7 @@ void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context) { struct kunit *test = try_catch->test; struct task_struct *task_struct; + struct completion *task_done; int exit_code, time_remaining; try_catch->context = context; @@ -75,13 +76,16 @@ void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context) return; } get_task_struct(task_struct); - wake_up_process(task_struct); /* * As for a vfork(2), task_struct->vfork_done (pointing to the * underlying kthread->exited) can be used to wait for the end of a - * kernel thread. + * kernel thread. It is set to NULL when the thread exits, so we + * keep a copy here. */ - time_remaining = wait_for_completion_timeout(task_struct->vfork_done, + task_done = task_struct->vfork_done; + wake_up_process(task_struct); + + time_remaining = wait_for_completion_timeout(task_done, kunit_test_timeout()); if (time_remaining == 0) { try_catch->try_result = -ETIMEDOUT;