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 [170.10.129.124]) by sourceware.org (Postfix) with ESMTPS id 4A0813858D28 for ; Tue, 14 Dec 2021 14:24:47 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 4A0813858D28 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-561-dH27xZkpMGa0bGb0vxaVjw-1; Tue, 14 Dec 2021 09:24:45 -0500 X-MC-Unique: dH27xZkpMGa0bGb0vxaVjw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 69A3F1015DA5; Tue, 14 Dec 2021 14:24:42 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.2.17.223]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 94DE35BE06; Tue, 14 Dec 2021 14:24:41 +0000 (UTC) From: Florian Weimer To: "H.J. Lu" Cc: "H.J. Lu via Libc-alpha" , Rongwei Wang Subject: Re: [PATCH] elf: Align argument of __munmap to page size [BZ #28676] References: <20211213152057.151438-1-hjl.tools@gmail.com> <3e6b30a4-cf8a-49c9-7382-3f3255c8201a@linux.alibaba.com> <87y24nskgi.fsf@oldenburg.str.redhat.com> Date: Tue, 14 Dec 2021 15:24:39 +0100 In-Reply-To: (H. J. Lu's message of "Tue, 14 Dec 2021 05:48:36 -0800") Message-ID: <877dc7qn6g.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-12.5 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_LOW, RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) 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-List-Received-Date: Tue, 14 Dec 2021 14:24:48 -0000 * H. J. Lu: > On Mon, Dec 13, 2021 at 11:40 PM Florian Weimer wrote: >> >> * H. J. Lu via Libc-alpha: >> >> > On Mon, Dec 13, 2021 at 6:49 PM Rongwei Wang >> > wrote: >> >> >> >> Hi, HJ >> >> >> >> Thanks for your help to fix this bug. And I just found out that the >> >> patch "elf: Properly align PT_LOAD segments" had been merged into >> >> glibc/master. >> >> >> >> And I saw Florian's email: >> >> >> >> > We should check munmap failure though and rollback everything if >> >> > necessary. It's possible we can undo the initial PROT_NONE mapping even >> >> > if future munmap calls fail because unmapping the first mapping does not >> >> > need to split a mapping. >> >> >> >> It seems rollback initial PROT_NONE mapping when munmap fails is good >> >> idea. Nice to have. Of course, IMO, this your patch is also can fix this >> >> munmap failure well. what do you think? >> >> >> >> When this fix is stable in glibc upstream, I will backport it into our >> >> internal glibc repo. So, if you have any improve this fix suggestions, I >> >> will respond immediately. Sorry for my speed is much slower than your. >> >> >> >> >> > >> > Let's wait for a few days. >> >> Can we please fix the regression in some way? It impacts development, >> particularly at this late stage during the 2.34 cycle. >> >> Either revert the change, or at least add the unchecked __munmap, and >> fix that later. > > What is the unchecked __munmap? The __munmap at the end: diff --git a/elf/dl-map-segments.h b/elf/dl-map-segments.h index 70a4c40695..54e606aa87 100644 --- a/elf/dl-map-segments.h +++ b/elf/dl-map-segments.h @@ -55,6 +55,7 @@ _dl_map_segment (const struct loadcmd *c, ElfW(Addr) mappref, if (delta) __munmap ((void *) map_start, delta); ElfW(Addr) map_end = map_start_aligned + maplength; + map_end = ALIGN_UP (map_end, GLRO(dl_pagesize)); delta = map_start + maplen - map_end; if (delta) __munmap ((void *) map_end, delta); Thanks, Florian