From patchwork Fri Jan 29 13:53:19 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Adhemerval Zanella X-Patchwork-Id: 60793 Delivered-To: patch@linaro.org Received: by 10.112.130.2 with SMTP id oa2csp1130679lbb; Fri, 29 Jan 2016 05:53:41 -0800 (PST) X-Received: by 10.66.102.8 with SMTP id fk8mr13571548pab.24.1454075621673; Fri, 29 Jan 2016 05:53:41 -0800 (PST) Return-Path: Received: from sourceware.org (server1.sourceware.org. [209.132.180.131]) by mx.google.com with ESMTPS id v16si948229pfa.129.2016.01.29.05.53.41 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 29 Jan 2016 05:53:41 -0800 (PST) Received-SPF: pass (google.com: domain of libc-alpha-return-66803-patch=linaro.org@sourceware.org designates 209.132.180.131 as permitted sender) client-ip=209.132.180.131; Authentication-Results: mx.google.com; spf=pass (google.com: domain of libc-alpha-return-66803-patch=linaro.org@sourceware.org designates 209.132.180.131 as permitted sender) smtp.mailfrom=libc-alpha-return-66803-patch=linaro.org@sourceware.org; dkim=pass header.i=@sourceware.org DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:from:to:subject:date:message-id; q=dns; s= default; b=FIAHTDTu2MKH0C/f/qwVV1eHFVkeJh0Lw4ZMtp3PFQc2LGv9EPlKI snumP7JD1W5Xbj9SreJxs0PCPmldx7RO/xiCZncnG8O7MEWwsZJ1MxOHgZ9YlWjK w1WF4IqAVQ7Slhmzga+TpjrNbUnVmlfJvAnJEdld0GqsOmrdHWTpKk= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:from:to:subject:date:message-id; s=default; bh=qD2/xQ20Trew42MLjUmB0DH3etE=; b=gCCKsK7cblrxBP6QGGQ7T98qAu4d Vbv0wMBfgdDenlFsEp1zeamdKQSxfb50ON73YLH+xmml4oZrmMlDmUK3EWZbOGj4 XD/th78Mw3F0DxQinoH5Kf2tPSPkHpPZQ8YSux+K8ND3JxSDxYD6aCXiKjt8+OO1 LqgBoYisCk5G2Z8= Received: (qmail 78208 invoked by alias); 29 Jan 2016 13:53:32 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 78176 invoked by uid 89); 29 Jan 2016 13:53:31 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.6 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_LOW, SPF_PASS autolearn=ham version=3.3.2 spammy=17, 8, 2627, va_list, 2945 X-HELO: mail-yk0-f175.google.com X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:subject:date:message-id; bh=A1nG9vJz93ch1PiYbP+CPf5Rbf22Q+faw2n75PByumQ=; b=P5NvQnFcPZTenuI2/Pdrm7yuIcn0cCSi943ZMrh9N5lFTiRVkN0TJBvUTtHCSBPscR FXHR8/fWhIBZWnL+WH60PKOsUDKFqKGnTltKa7ZihKS4k8xuZeRQUrF1QzEIJ9mwJlKU 8e4Bm9Z0aeQTrcwGe0enyePVA/puGRHhavElW40WRlKBZqUq7mtrP1amlzrY0r2w5g8n 9bf4IS1bdIFBiFLvaH/fcw/1ldVjYRxFPSLE/SZ7dV+tFS7//LmI26WPua2kohDtZqHS hiDJWkTSEisYoZCrpJ90Xi1OYVODg/jcGAtkl1NoEVcnZgpmiysPDpsIxY2Y9o/wfK/Q zfGg== X-Gm-Message-State: AG10YORvBl7snrzJ+WmjBxesbf7PKcNAWzkIep0Uo9oxHlpmnnSHj0cGDk/axpkq4KHZOFNT X-Received: by 10.129.57.135 with SMTP id g129mr4349785ywa.244.1454075607384; Fri, 29 Jan 2016 05:53:27 -0800 (PST) From: Adhemerval Zanella To: libc-alpha@sourceware.org Subject: [PATCH] posix: Remove dynamic memory allocation from execl{e,p} Date: Fri, 29 Jan 2016 11:53:19 -0200 Message-Id: <1454075599-2304-1-git-send-email-adhemerval.zanella@linaro.org> GLIBC execl{e,p} implementation might use malloc if the total number of arguments exceeds initial assumption size (1024). This might lead to issues in two situations: 1. execl/execle is stated to be async-signal-safe by POSIX [1]. However if it is used in a signal handler with a large argument set (that may call malloc internally) and the resulting call fails, it might lead malloc in the program in a bad state. 2. If the functions are used in a vfork/clone(VFORK) situation it also might break internal malloc state from parent. This patch fixes it by using stack allocation instead. It fixes BZ#19534. One caveat is current stack allocation allocation limit the patch is using is based on previous posix_spawn{p}/execvpe comments to use internal __MAX_ALLOCA_CUTOFF definition. It is an arbitrary value that limits total argument handlings to 8192 for 32-bits and 4096 for 64-bits. I think it would be better to increase this value for higher threshold, either by increasing the __MAX_ALLOCA_CUTOFF value or using a different strategy to limit stack allocation on exec functions. Tested on x86_64. [1] http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html [BZ #19534] * posix/execl.c (execl): Remove dynamic memory allocation. * posix/execle.c (execle): Likewise. * posix/execlp.c (execlp): Likewise. --- ChangeLog | 5 +++++ posix/execl.c | 70 ++++++++++++++++++++------------------------------------- posix/execle.c | 71 +++++++++++++++++++++------------------------------------- posix/execlp.c | 69 ++++++++++++++++++++------------------------------------ 4 files changed, 78 insertions(+), 137 deletions(-) -- 1.9.1 diff --git a/posix/execl.c b/posix/execl.c index 102d19d..26c28e1 100644 --- a/posix/execl.c +++ b/posix/execl.c @@ -16,58 +16,36 @@ . */ #include +#include #include -#include -#include -#include - -#include - +#include /* Execute PATH with all arguments after PATH until a NULL pointer and environment from `environ'. */ int execl (const char *path, const char *arg, ...) { -#define INITIAL_ARGV_MAX 1024 - size_t argv_max = INITIAL_ARGV_MAX; - const char *initial_argv[INITIAL_ARGV_MAX]; - const char **argv = initial_argv; - va_list args; - - argv[0] = arg; - - va_start (args, arg); - unsigned int i = 0; - while (argv[i++] != NULL) - { - if (i == argv_max) - { - argv_max *= 2; - const char **nptr = realloc (argv == initial_argv ? NULL : argv, - argv_max * sizeof (const char *)); - if (nptr == NULL) - { - if (argv != initial_argv) - free (argv); - va_end (args); - return -1; - } - if (argv == initial_argv) - /* We have to copy the already filled-in data ourselves. */ - memcpy (nptr, argv, i * sizeof (const char *)); - - argv = nptr; - } - - argv[i] = va_arg (args, const char *); - } - va_end (args); - - int ret = __execve (path, (char *const *) argv, __environ); - if (argv != initial_argv) - free (argv); - - return ret; + int argc; + int limit = MIN (NCARGS, __MAX_ALLOCA_CUTOFF / sizeof (char *)); + va_list ap; + va_start (ap, arg); + for (argc = 1; va_arg (ap, const char *); argc++) + if (argc+1 >= limit) + { + errno = E2BIG; + return -1; + } + va_end (ap); + + int i; + char *argv[argc+1]; + va_start (ap, arg); + argv[0] = (char*) arg; + for (i = 1; i < argc; i++) + argv[i] = va_arg (ap, char *); + argv[i] = NULL; + va_end (ap); + + return __execve (path, argv, __environ); } libc_hidden_def (execl) diff --git a/posix/execle.c b/posix/execle.c index 8edc03a..79c13e3 100644 --- a/posix/execle.c +++ b/posix/execle.c @@ -17,57 +17,36 @@ #include #include -#include -#include -#include - -#include +#include +#include /* Execute PATH with all arguments after PATH until a NULL pointer, and the argument after that for environment. */ int execle (const char *path, const char *arg, ...) { -#define INITIAL_ARGV_MAX 1024 - size_t argv_max = INITIAL_ARGV_MAX; - const char *initial_argv[INITIAL_ARGV_MAX]; - const char **argv = initial_argv; - va_list args; - argv[0] = arg; - - va_start (args, arg); - unsigned int i = 0; - while (argv[i++] != NULL) - { - if (i == argv_max) - { - argv_max *= 2; - const char **nptr = realloc (argv == initial_argv ? NULL : argv, - argv_max * sizeof (const char *)); - if (nptr == NULL) - { - if (argv != initial_argv) - free (argv); - va_end (args); - return -1; - } - if (argv == initial_argv) - /* We have to copy the already filled-in data ourselves. */ - memcpy (nptr, argv, i * sizeof (const char *)); - - argv = nptr; - } - - argv[i] = va_arg (args, const char *); - } - - const char *const *envp = va_arg (args, const char *const *); - va_end (args); - - int ret = __execve (path, (char *const *) argv, (char *const *) envp); - if (argv != initial_argv) - free (argv); - - return ret; + int argc; + int limit = MIN (NCARGS, __MAX_ALLOCA_CUTOFF / sizeof (char *)); + va_list ap; + va_start (ap, arg); + for (argc = 1; va_arg (ap, const char *); argc++) + if (argc+1 >= limit) + { + errno = E2BIG; + return -1; + } + va_end (ap); + + int i; + char *argv[argc+1]; + char **envp; + va_start (ap, arg); + argv[0] = (char*) arg; + for (i = 1; i < argc; i++) + argv[i] = va_arg (ap, char *); + envp = va_arg (ap, char **); + va_end (ap); + + return __execve (path, argv, envp); } libc_hidden_def (execle) diff --git a/posix/execlp.c b/posix/execlp.c index 6700994..a4b603c 100644 --- a/posix/execlp.c +++ b/posix/execlp.c @@ -17,11 +17,8 @@ #include #include -#include -#include -#include - -#include +#include +#include /* Execute FILE, searching in the `PATH' environment variable if it contains no slashes, with all arguments after FILE until a @@ -29,45 +26,27 @@ int execlp (const char *file, const char *arg, ...) { -#define INITIAL_ARGV_MAX 1024 - size_t argv_max = INITIAL_ARGV_MAX; - const char *initial_argv[INITIAL_ARGV_MAX]; - const char **argv = initial_argv; - va_list args; - - argv[0] = arg; - - va_start (args, arg); - unsigned int i = 0; - while (argv[i++] != NULL) - { - if (i == argv_max) - { - argv_max *= 2; - const char **nptr = realloc (argv == initial_argv ? NULL : argv, - argv_max * sizeof (const char *)); - if (nptr == NULL) - { - if (argv != initial_argv) - free (argv); - va_end (args); - return -1; - } - if (argv == initial_argv) - /* We have to copy the already filled-in data ourselves. */ - memcpy (nptr, argv, i * sizeof (const char *)); - - argv = nptr; - } - - argv[i] = va_arg (args, const char *); - } - va_end (args); - - int ret = execvp (file, (char *const *) argv); - if (argv != initial_argv) - free (argv); - - return ret; + int argc; + int limit = MIN (NCARGS, __MAX_ALLOCA_CUTOFF / sizeof (char *)); + va_list ap; + va_start (ap, arg); + for (argc = 1; va_arg (ap, const char *); argc++) + if (argc+1 >= limit) + { + errno = E2BIG; + return -1; + } + va_end (ap); + + int i; + char *argv[argc+1]; + va_start (ap, arg); + argv[0] = (char*) arg; + for (i = 1; i < argc; i++) + argv[i] = va_arg (ap, char *); + argv[i] = NULL; + va_end (ap); + + return __execvpe (file, argv, __environ); } libc_hidden_def (execlp)