From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by sourceware.org (Postfix) with ESMTPS id 235313850438 for ; Mon, 5 Jun 2023 13:29:49 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 235313850438 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1685971788; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=+7eM6v4Vi/gteh7EjD0BS4RKBJviG9xQZCJ1JxojBZo=; b=fiAIbN06C7Mel5BDO/lMWMHWYfaCYi8pZNblHM3ddodqFCmq9Lj1IVTfFWNrJEQ1g3+7C1 EKLJTWK4FZn3Z1PgCRwgsUDezdPqeKE49kqHfRiCwVVTjGyJULrVBvMmCBca77INeaVUyw lmphOlqTYCLUul/vn/hLB6BmPZ75Hb4= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-346-m8lnNGouOQui3t-r8AN7jw-1; Mon, 05 Jun 2023 09:29:47 -0400 X-MC-Unique: m8lnNGouOQui3t-r8AN7jw-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 627E9802355; Mon, 5 Jun 2023 13:29:47 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.2.16.27]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A8927492B00; Mon, 5 Jun 2023 13:29:46 +0000 (UTC) From: Florian Weimer To: Joe Simmons-Talbott via Libc-alpha Cc: Joe Simmons-Talbott , Samuel Thibault , Sergey Bugaev Subject: Re: [PATCH] grantpt: Get rid of alloca References: <20230601195817.3251303-1-josimmon@redhat.com> Date: Mon, 05 Jun 2023 15:29:45 +0200 In-Reply-To: <20230601195817.3251303-1-josimmon@redhat.com> (Joe Simmons-Talbott via Libc-alpha's message of "Thu, 1 Jun 2023 15:58:17 -0400") Message-ID: <87ttvmyr3q.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-10.5 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,GIT_PATCH_0,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_NONE,TXREP,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: * Joe Simmons-Talbott via Libc-alpha: > Replace alloca with a scratch_buffer to avoid potential stack overflows. > --- > sysdeps/unix/grantpt.c | 12 +++++++++++- > 1 file changed, 11 insertions(+), 1 deletion(-) > > diff --git a/sysdeps/unix/grantpt.c b/sysdeps/unix/grantpt.c > index 38fce52576..e5d2390bf2 100644 > --- a/sysdeps/unix/grantpt.c > +++ b/sysdeps/unix/grantpt.c > @@ -20,6 +20,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -147,7 +148,14 @@ grantpt (int fd) > /* `sysconf' does not support _SC_GETGR_R_SIZE_MAX. > Try a moderate value. */ > grbuflen = 1024; > - grtmpbuf = (char *) __alloca (grbuflen); > + struct scratch_buffer sbuf; > + scratch_buffer_init (&sbuf); > + if (!scratch_buffer_set_array_size (&sbuf, 1, grbuflen)) > + { > + retval -1; > + goto cleanup; > + } > + grtmpbuf = sbuf.data; > __getgrnam_r (TTY_GROUP, &grbuf, grtmpbuf, grbuflen, &p); > if (p != NULL) > tty_gid = p->gr_gid; > @@ -255,6 +263,8 @@ grantpt (int fd) > if (buf != _buf) > free (buf); > > + scratch_buffer_free(sbuf); > + > return retval; > } > libc_hidden_def (grantpt) How did you test this? This code is only used on Hurd due to the override in sysdeps/unix/sysv/linux/grantpt.c. Maybe the hurd maintainers could review this change? Thanks, Florian