From patchwork Sat Mar 15 07:42:09 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michael Tokarev X-Patchwork-Id: 14017795 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 8ACE2C28B28 for ; Sat, 15 Mar 2025 07:43:33 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ttMAo-00022b-9r; Sat, 15 Mar 2025 03:43:10 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ttMAl-0001zA-Sa; Sat, 15 Mar 2025 03:43:08 -0400 Received: from isrv.corpit.ru ([86.62.121.231]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ttMAj-0004nC-PM; Sat, 15 Mar 2025 03:43:07 -0400 Received: from tsrv.corpit.ru (tsrv.tls.msk.ru [192.168.177.2]) by isrv.corpit.ru (Postfix) with ESMTP id 9A9DEFFAFB; Sat, 15 Mar 2025 10:41:55 +0300 (MSK) Received: from gandalf.tls.msk.ru (mjt.wg.tls.msk.ru [192.168.177.130]) by tsrv.corpit.ru (Postfix) with ESMTP id 895E31CACC5; Sat, 15 Mar 2025 10:42:49 +0300 (MSK) Received: by gandalf.tls.msk.ru (Postfix, from userid 1000) id 6930F559E2; Sat, 15 Mar 2025 10:42:49 +0300 (MSK) From: Michael Tokarev To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, Richard Henderson , Michael Tokarev Subject: [Stable-8.2.10 07/42] linux-user: Honor elf alignment when placing images Date: Sat, 15 Mar 2025 10:42:09 +0300 Message-Id: <20250315074249.634718-7-mjt@tls.msk.ru> X-Mailer: git-send-email 2.39.5 In-Reply-To: References: MIME-Version: 1.0 Received-SPF: pass client-ip=86.62.121.231; envelope-from=mjt@tls.msk.ru; helo=isrv.corpit.ru X-Spam_score_int: -68 X-Spam_score: -6.9 X-Spam_bar: ------ X-Spam_report: (-6.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_HI=-5, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org From: Richard Henderson Most binaries don't actually depend on more than page alignment, but any binary can request it. Not honoring this was a bug. This became obvious when gdb reported Failed to read a valid object file image from memory when examining some vdso which are marked as needing more than page alignment. Signed-off-by: Richard Henderson (cherry picked from commit c81d1fafa6233448bcc2d8fcd2ba63a4ae834f3a) Signed-off-by: Michael Tokarev diff --git a/linux-user/elfload.c b/linux-user/elfload.c index 17cd547c0c..e1a8b102d4 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -3278,7 +3278,8 @@ static void load_elf_image(const char *image_name, const ImageSource *src, char **pinterp_name) { g_autofree struct elf_phdr *phdr = NULL; - abi_ulong load_addr, load_bias, loaddr, hiaddr, error; + abi_ulong load_addr, load_bias, loaddr, hiaddr, error, align; + size_t reserve_size, align_size; int i, prot_exec; Error *err = NULL; @@ -3362,6 +3363,9 @@ static void load_elf_image(const char *image_name, const ImageSource *src, load_addr = loaddr; + align = pow2ceil(info->alignment); + info->alignment = align; + if (pinterp_name != NULL) { if (ehdr->e_type == ET_EXEC) { /* @@ -3370,8 +3374,6 @@ static void load_elf_image(const char *image_name, const ImageSource *src, */ probe_guest_base(image_name, loaddr, hiaddr); } else { - abi_ulong align; - /* * The binary is dynamic, but we still need to * select guest_base. In this case we pass a size. @@ -3389,10 +3391,7 @@ static void load_elf_image(const char *image_name, const ImageSource *src, * Since we do not have complete control over the guest * address space, we prefer the kernel to choose some address * rather than force the use of LOAD_ADDR via MAP_FIXED. - * But without MAP_FIXED we cannot guarantee alignment, - * only suggest it. */ - align = pow2ceil(info->alignment); if (align) { load_addr &= -align; } @@ -3416,13 +3415,35 @@ static void load_elf_image(const char *image_name, const ImageSource *src, * In both cases, we will overwrite pages in this range with mappings * from the executable. */ - load_addr = target_mmap(load_addr, (size_t)hiaddr - loaddr + 1, PROT_NONE, + reserve_size = (size_t)hiaddr - loaddr + 1; + align_size = reserve_size; + + if (ehdr->e_type != ET_EXEC && align > qemu_real_host_page_size()) { + align_size += align - 1; + } + + load_addr = target_mmap(load_addr, align_size, PROT_NONE, MAP_PRIVATE | MAP_ANON | MAP_NORESERVE | (ehdr->e_type == ET_EXEC ? MAP_FIXED_NOREPLACE : 0), -1, 0); if (load_addr == -1) { goto exit_mmap; } + + if (align_size != reserve_size) { + abi_ulong align_addr = ROUND_UP(load_addr, align); + abi_ulong align_end = align_addr + reserve_size; + abi_ulong load_end = load_addr + align_size; + + if (align_addr != load_addr) { + target_munmap(load_addr, align_addr - load_addr); + } + if (align_end != load_end) { + target_munmap(align_end, load_end - align_end); + } + load_addr = align_addr; + } + load_bias = load_addr - loaddr; if (elf_is_fdpic(ehdr)) {