From mboxrd@z Thu Jan 1 00:00:00 1970 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 49E23C433FE for ; Mon, 3 Oct 2022 07:33:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231551AbiJCHd2 (ORCPT ); Mon, 3 Oct 2022 03:33:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55088 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231461AbiJCHcp (ORCPT ); Mon, 3 Oct 2022 03:32:45 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 76B4C25298; Mon, 3 Oct 2022 00:21:11 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 97426B80E94; Mon, 3 Oct 2022 07:19:28 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0074DC433D6; Mon, 3 Oct 2022 07:19:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1664781567; bh=tfBx23GHH+xKpCPewZ/4fGyE9B3qjYdkoAWuEz5Cfwk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=y3g9NWyRNgifvFYKztx7L9v0llVDkbXoHIG79wLwzRfsxWbOgYbglrJVgB8hsrkYB BlgfBEqEgQG+8y7Njwth7LrIcTS6DLAO7j4vmIMr9WpMtgwO7Y3h4Bw+XEyAVSYkqH FHLMVgwsarpzs5mESp3HYCx7827AcgTTgtmiJvNQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Al Viro , Sasha Levin Subject: [PATCH 5.15 67/83] dont use __kernel_write() on kmap_local_page() Date: Mon, 3 Oct 2022 09:11:32 +0200 Message-Id: <20221003070723.675440372@linuxfoundation.org> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20221003070721.971297651@linuxfoundation.org> References: <20221003070721.971297651@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Al Viro [ Upstream commit 06bbaa6dc53cb72040db952053432541acb9adc7 ] passing kmap_local_page() result to __kernel_write() is unsafe - random ->write_iter() might (and 9p one does) get unhappy when passed ITER_KVEC with pointer that came from kmap_local_page(). Fix by providing a variant of __kernel_write() that takes an iov_iter from caller (__kernel_write() becomes a trivial wrapper) and adding dump_emit_page() that parallels dump_emit(), except that instead of __kernel_write() it uses __kernel_write_iter() with ITER_BVEC source. Fixes: 3159ed57792b "fs/coredump: use kmap_local_page()" Signed-off-by: Al Viro Signed-off-by: Sasha Levin --- fs/coredump.c | 38 +++++++++++++++++++++++++++++++++----- fs/internal.h | 3 +++ fs/read_write.c | 22 ++++++++++++++-------- 3 files changed, 50 insertions(+), 13 deletions(-) diff --git a/fs/coredump.c b/fs/coredump.c index 26eb5a095832..43fdd82f82ab 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -902,6 +902,38 @@ static int __dump_skip(struct coredump_params *cprm, size_t nr) } } +static int dump_emit_page(struct coredump_params *cprm, struct page *page) +{ + struct bio_vec bvec = { + .bv_page = page, + .bv_offset = 0, + .bv_len = PAGE_SIZE, + }; + struct iov_iter iter; + struct file *file = cprm->file; + loff_t pos = file->f_pos; + ssize_t n; + + if (cprm->to_skip) { + if (!__dump_skip(cprm, cprm->to_skip)) + return 0; + cprm->to_skip = 0; + } + if (cprm->written + PAGE_SIZE > cprm->limit) + return 0; + if (dump_interrupted()) + return 0; + iov_iter_bvec(&iter, WRITE, &bvec, 1, PAGE_SIZE); + n = __kernel_write_iter(cprm->file, &iter, &pos); + if (n != PAGE_SIZE) + return 0; + file->f_pos = pos; + cprm->written += PAGE_SIZE; + cprm->pos += PAGE_SIZE; + + return 1; +} + int dump_emit(struct coredump_params *cprm, const void *addr, int nr) { if (cprm->to_skip) { @@ -933,7 +965,6 @@ int dump_user_range(struct coredump_params *cprm, unsigned long start, for (addr = start; addr < start + len; addr += PAGE_SIZE) { struct page *page; - int stop; /* * To avoid having to allocate page tables for virtual address @@ -944,10 +975,7 @@ int dump_user_range(struct coredump_params *cprm, unsigned long start, */ page = get_dump_page(addr); if (page) { - void *kaddr = kmap_local_page(page); - - stop = !dump_emit(cprm, kaddr, PAGE_SIZE); - kunmap_local(kaddr); + int stop = !dump_emit_page(cprm, page); put_page(page); if (stop) return 0; diff --git a/fs/internal.h b/fs/internal.h index 4f1fe6d08866..69b64136ae4c 100644 --- a/fs/internal.h +++ b/fs/internal.h @@ -16,6 +16,7 @@ struct shrink_control; struct fs_context; struct user_namespace; struct pipe_inode_info; +struct iov_iter; /* * block/bdev.c @@ -219,3 +220,5 @@ struct xattr_ctx { int setxattr_copy(const char __user *name, struct xattr_ctx *ctx); int do_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry, struct xattr_ctx *ctx); + +ssize_t __kernel_write_iter(struct file *file, struct iov_iter *from, loff_t *pos); diff --git a/fs/read_write.c b/fs/read_write.c index 8d3ec975514d..08299a8f3e05 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -512,14 +512,9 @@ static ssize_t new_sync_write(struct file *filp, const char __user *buf, size_t } /* caller is responsible for file_start_write/file_end_write */ -ssize_t __kernel_write(struct file *file, const void *buf, size_t count, loff_t *pos) +ssize_t __kernel_write_iter(struct file *file, struct iov_iter *from, loff_t *pos) { - struct kvec iov = { - .iov_base = (void *)buf, - .iov_len = min_t(size_t, count, MAX_RW_COUNT), - }; struct kiocb kiocb; - struct iov_iter iter; ssize_t ret; if (WARN_ON_ONCE(!(file->f_mode & FMODE_WRITE))) @@ -535,8 +530,7 @@ ssize_t __kernel_write(struct file *file, const void *buf, size_t count, loff_t init_sync_kiocb(&kiocb, file); kiocb.ki_pos = pos ? *pos : 0; - iov_iter_kvec(&iter, WRITE, &iov, 1, iov.iov_len); - ret = file->f_op->write_iter(&kiocb, &iter); + ret = file->f_op->write_iter(&kiocb, from); if (ret > 0) { if (pos) *pos = kiocb.ki_pos; @@ -546,6 +540,18 @@ ssize_t __kernel_write(struct file *file, const void *buf, size_t count, loff_t inc_syscw(current); return ret; } + +/* caller is responsible for file_start_write/file_end_write */ +ssize_t __kernel_write(struct file *file, const void *buf, size_t count, loff_t *pos) +{ + struct kvec iov = { + .iov_base = (void *)buf, + .iov_len = min_t(size_t, count, MAX_RW_COUNT), + }; + struct iov_iter iter; + iov_iter_kvec(&iter, WRITE, &iov, 1, iov.iov_len); + return __kernel_write_iter(file, &iter, pos); +} /* * This "EXPORT_SYMBOL_GPL()" is more of a "EXPORT_SYMBOL_DONTUSE()", * but autofs is one of the few internal kernel users that actually -- 2.35.1