From patchwork Tue Feb 28 23:42:46 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jack Pearson X-Patchwork-Id: 65816 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id CD3093858D3C for ; Tue, 28 Feb 2023 23:43:45 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org CD3093858D3C DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1677627825; bh=QXnWbSCpWkTmls8MMTgCQF5ydZd6lokrtdxQAOaVSKQ=; h=To:Cc:Subject:Date:List-Id:List-Unsubscribe:List-Archive: List-Post:List-Help:List-Subscribe:From:Reply-To:From; b=L41sh2Asp/TiyDEnjk+3JCyekPofQYklZXf8bPZkJ/TwSZsfSRsVZ6MDf0Gz4fIn1 dal95Chtmu8PrlIgLi9+x7Wfdh5AUcuWVNOPcIKHc+9UDk1kvs7ixa3vXjbHxMcS6o gT3QdJQv4MgwErVbLI4fdhA6HcdxhVMhiJHSLVss= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from hosted.mailcow.de (hosted.mailcow.de [5.1.76.202]) by sourceware.org (Postfix) with ESMTPS id C86673858D33 for ; Tue, 28 Feb 2023 23:43:20 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org C86673858D33 Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 3425C5C0569; Wed, 1 Mar 2023 00:43:15 +0100 (CET) To: Alex Colomar , linux-man@vger.kernel.org, GNU C Library , Carlos O'Donell Cc: Jack Pearson Subject: [PATCH] clone.2: note EINVAL when exit_signal + bad flags Date: Tue, 28 Feb 2023 15:42:46 -0800 Message-Id: <20230228234246.466811-1-jack@pearson.onl> MIME-Version: 1.0 X-Spam-Status: No, score=-11.5 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_DNSWL_LOW, SPF_HELO_PASS, TXREP, T_SPF_PERMERROR autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Jack Pearson via Libc-alpha From: Jack Pearson Reply-To: Jack Pearson Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" Document that Linux will report EINVAL when exit_signal is specified and either CLONE_THREAD or CLONE_PARENT is specified. From clone3_args_valid in Linux: ``` if ((kargs->flags & (CLONE_THREAD | CLONE_PARENT)) && kargs->exit_signal) return false; ``` I have verified that this happens on my kernel with a small program: ``` #include #include #include #include #include int main() { struct clone_args ca = { .flags = CLONE_THREAD | CLONE_SIGHAND | CLONE_VM, .exit_signal = SIGCHLD, // comment me out to fix error .set_tid_size = 0, }; syscall(SYS_clone3, &ca, sizeof(struct clone_args)); perror(""); } ``` And I have verified that this doesn't happen with normal `clone` through the glibc helper: ``` #define _GNU_SOURCE #include #include #include #include int do_nothing(void *_) { return 0; } int main() { void *map = mmap(NULL, 0x10000, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0); void *stack_top = map + 0x10000 - 1; clone(do_nothing, stack_top, CLONE_THREAD | CLONE_VM | CLONE_SIGHAND | SIGCHLD, NULL); perror(""); } ``` Signed-off-by: Jack Pearson --- man2/clone.2 | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/man2/clone.2 b/man2/clone.2 index d63895189..be802a280 100644 --- a/man2/clone.2 +++ b/man2/clone.2 @@ -1436,6 +1436,16 @@ One of the PIDs specified in .I set_tid was an invalid. .TP +.BR EINVAL " (" clone3 "() only)" +.\" commit 7f192e3cd316ba58c88dfa26796cf77789dd9872 +.B CLONE_THREAD +or +.B CLONE_PARENT +was specified in the +.I flags +mask, but a signal was specified in +.I exit_signal. +.TP .BR EINVAL " (AArch64 only, Linux 4.6 and earlier)" .I stack was not aligned to a 128-bit boundary.