From patchwork Thu Dec 9 19:29:17 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "H.J. Lu" X-Patchwork-Id: 48721 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 B646F385800E for ; Thu, 9 Dec 2021 19:29:42 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org B646F385800E DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1639078182; bh=VgHvRRA/2Hstr15t98jaM2SKP/Wa557VNavmf1MnzXQ=; h=Date:To:Subject:References:In-Reply-To:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To: From; b=IyXCrP0NdZCRdpsXI3h9eT8Ji55rKyqqREVnnO8inmtNc8OMLVRWCAYjBG08QVH6K pmaMcTl+HDqNsIuw1/8Gns8Xw043YgevRrHOhR8KW7LHvXTxInVWUv6Fmepkbgo5Bg AY9s6v4t5ECOg/NcZhyWJ1GtGOHBwVr+g+IGlOxo= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from mail-pf1-x429.google.com (mail-pf1-x429.google.com [IPv6:2607:f8b0:4864:20::429]) by sourceware.org (Postfix) with ESMTPS id 12C003858C3A for ; Thu, 9 Dec 2021 19:29:20 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 12C003858C3A Received: by mail-pf1-x429.google.com with SMTP id k64so6305531pfd.11 for ; Thu, 09 Dec 2021 11:29:20 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=VgHvRRA/2Hstr15t98jaM2SKP/Wa557VNavmf1MnzXQ=; b=1TsCA9+OMdruSIwu88ZUfVPK9wOPQQaphxR6bPJHaajVzTZZ4I6K90LxRT0Ahlca78 fhJJupKgGmEPqyGpcrD+Lx4QXYByPaUdk1KSwmNISDdR8aLvukETt6O4Iy+lu0KB63VM CrXcBi4QeeFzaL0RnnE8JGb3XRLpI2obdIFJeIEp1QmBMqWVNdbWTVUdA/vRdLAduTXb GkI8V7CnXnrF2/QIBzrVRTqflc4o6sLGBJSkaJnYpyJTBYEmldEE/iHJWXIX6KQtG2NS XaWR0QRYERtfVpqjGK+XKy5W+2pLbpmggFksADLi6udUwMZjqbTn12jr9ejBFvR3elN7 1hDQ== X-Gm-Message-State: AOAM530yWW2Rjjt0uuDO6Gf99YOpI2qpkjXGiWM5Sm1uoGIOGhPvv3NZ Domw1DfPxLjOqqkN740V4zQ= X-Google-Smtp-Source: ABdhPJwbDORQfzJYeT7eCcyTd+F0/Dq34Kun0NNoQv0wYLVx00ygnf55S8aOI52GCUiQrleCAgQXLQ== X-Received: by 2002:a63:465c:: with SMTP id v28mr27867887pgk.311.1639078159047; Thu, 09 Dec 2021 11:29:19 -0800 (PST) Received: from gnu-cfl-2.localdomain ([172.58.35.133]) by smtp.gmail.com with ESMTPSA id mv22sm406474pjb.36.2021.12.09.11.29.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Dec 2021 11:29:18 -0800 (PST) Received: by gnu-cfl-2.localdomain (Postfix, from userid 1000) id 9F927420971; Thu, 9 Dec 2021 11:29:17 -0800 (PST) Date: Thu, 9 Dec 2021 11:29:17 -0800 To: Rongwei Wang , GNU C Library , Florian Weimer , xuyu@linux.alibaba.com, gavin.dg@linux.alibaba.com Subject: [PATCH v4] elf: Properly align PT_LOAD segments [BZ #28676] Message-ID: References: <20211209055719.56245-1-rongwei.wang@linux.alibaba.com> <20211209055719.56245-2-rongwei.wang@linux.alibaba.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Spam-Status: No, score=-3029.6 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, GIT_PATCH_0, RCVD_IN_BARRACUDACENTRAL, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, 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-Patchwork-Original-From: "H.J. Lu via Libc-alpha" From: "H.J. Lu" Reply-To: "H.J. Lu" Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" On Thu, Dec 09, 2021 at 10:04:32AM -0800, H.J. Lu wrote: > On Thu, Dec 09, 2021 at 07:14:10AM -0800, H.J. Lu wrote: > > Hi, > > I updated your patch. Please take a look. > > > H.J. > -- > When PT_LOAD segment alignment > the page size, allocate enough space > to ensure that the segment can be properly aligned. > > This fixes [BZ #28676]. H.J. --- Changes in v4: 1. Call unmap when the second mmap fails. When PT_LOAD segment alignment > the page size, allocate enough space to ensure that the segment can be properly aligned. This fixes [BZ #28676]. --- elf/dl-load.c | 1 + elf/dl-load.h | 2 +- elf/dl-map-segments.h | 49 +++++++++++++++++++++++++++++++++++++++---- 3 files changed, 47 insertions(+), 5 deletions(-) diff --git a/elf/dl-load.c b/elf/dl-load.c index bf8957e73c..9a23590bf4 100644 --- a/elf/dl-load.c +++ b/elf/dl-load.c @@ -1150,6 +1150,7 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd, c->mapend = ALIGN_UP (ph->p_vaddr + ph->p_filesz, GLRO(dl_pagesize)); c->dataend = ph->p_vaddr + ph->p_filesz; c->allocend = ph->p_vaddr + ph->p_memsz; + c->mapalign = ph->p_align; c->mapoff = ALIGN_DOWN (ph->p_offset, GLRO(dl_pagesize)); /* Determine whether there is a gap between the last segment diff --git a/elf/dl-load.h b/elf/dl-load.h index e329d49a81..c121e3456c 100644 --- a/elf/dl-load.h +++ b/elf/dl-load.h @@ -74,7 +74,7 @@ ELF_PREFERRED_ADDRESS_DATA; Its details have been expanded out and converted. */ struct loadcmd { - ElfW(Addr) mapstart, mapend, dataend, allocend; + ElfW(Addr) mapstart, mapend, dataend, allocend, mapalign; ElfW(Off) mapoff; int prot; /* PROT_* bits. */ }; diff --git a/elf/dl-map-segments.h b/elf/dl-map-segments.h index f9fb110ee3..f710cf2e48 100644 --- a/elf/dl-map-segments.h +++ b/elf/dl-map-segments.h @@ -18,6 +18,50 @@ #include +/* Map a segment and align it properly. */ + +static __always_inline ElfW(Addr) +_dl_map_segment (const struct loadcmd *c, ElfW(Addr) mappref, + const size_t maplength, int fd) +{ + if (__glibc_likely (c->mapalign <= GLRO(dl_pagesize))) + return (ElfW(Addr)) __mmap ((void *) mappref, maplength, c->prot, + MAP_COPY|MAP_FILE, fd, c->mapoff); + + /* If the segment alignment > the page size, allocate enough space to + ensure that the segment can be properly aligned. */ + ElfW(Addr) maplen = (maplength >= c->mapalign + ? (maplength + c->mapalign) + : (2 * c->mapalign)); + ElfW(Addr) map_start = (ElfW(Addr)) __mmap ((void *) mappref, maplen, + PROT_NONE, + MAP_ANONYMOUS|MAP_PRIVATE, + -1, 0); + if (__glibc_unlikely ((void *) map_start == MAP_FAILED)) + return map_start; + + ElfW(Addr) map_start_aligned = ALIGN_UP (map_start, c->mapalign); + map_start_aligned = (ElfW(Addr)) __mmap ((void *) map_start_aligned, + maplength, c->prot, + MAP_COPY|MAP_FILE|MAP_FIXED, + fd, c->mapoff); + if (__glibc_unlikely ((void *) map_start == MAP_FAILED)) + __munmap ((void *) map_start, maplen); + else + { + /* Unmap the unused regions. */ + ElfW(Addr) delta = map_start_aligned - map_start; + if (delta) + __munmap ((void *) map_start, delta); + ElfW(Addr) map_end = map_start_aligned + maplength; + delta = map_start + maplen - map_end; + if (delta) + __munmap ((void *) map_end, delta); + } + + return map_start_aligned; +} + /* This implementation assumes (as does the corresponding implementation of _dl_unmap_segments, in dl-unmap-segments.h) that shared objects are always laid out with all segments contiguous (or with gaps @@ -53,10 +97,7 @@ _dl_map_segments (struct link_map *l, int fd, - MAP_BASE_ADDR (l)); /* Remember which part of the address space this object uses. */ - l->l_map_start = (ElfW(Addr)) __mmap ((void *) mappref, maplength, - c->prot, - MAP_COPY|MAP_FILE, - fd, c->mapoff); + l->l_map_start = _dl_map_segment (c, mappref, maplength, fd); if (__glibc_unlikely ((void *) l->l_map_start == MAP_FAILED)) return DL_MAP_SEGMENTS_ERROR_MAP_SEGMENT;