From nobody Mon Apr 13 08:04:22 2026 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 7EE19C6FD1F for ; Wed, 22 Mar 2023 14:56:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230214AbjCVO42 (ORCPT ); Wed, 22 Mar 2023 10:56:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60226 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230396AbjCVOzz (ORCPT ); Wed, 22 Mar 2023 10:55:55 -0400 Received: from mail-wm1-x32c.google.com (mail-wm1-x32c.google.com [IPv6:2a00:1450:4864:20::32c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0502410AAA; Wed, 22 Mar 2023 07:55:37 -0700 (PDT) Received: by mail-wm1-x32c.google.com with SMTP id o32so5337843wms.1; Wed, 22 Mar 2023 07:55:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; t=1679496935; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=CnqbASwlTwT+hpjobkOVo9MU5RGxoqqRsLFO5z2uP7A=; b=VYs6ugG87mfTKeYAZszhJ4zHVIrm5oSCM3SiOaM9Rb9+Z4kqLzTtkkPo8FkMnjaQCi Au5clGPac1dlx+ijIXPxu1kRuLlDQGOIGWa8EaA80xeGft1ma8F76vHwldlxfSFH771D WrXTC3+cKYn5NAe7KlQKnRR/gAsZUgXpQRW+/c4MTlEJInNTG7CleO8s1pxN2sBuyD1N IIYWjMBNLIvRvfR4qduXhFYFHEKbVgFkPDvyGuEOozXYaBzCj51XyHEhZhfq4n5Avnqe 217YR8GkTStFxKUVA9XWDGV9JiUUt9MLAhCTJQfbektBiHj2p1bZYldccVgn1o6LyIGG LWRg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1679496935; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=CnqbASwlTwT+hpjobkOVo9MU5RGxoqqRsLFO5z2uP7A=; b=uD4tx0z0r0bE8O253Ybvi9hibYF6wMjgQd7OaTuB36eHEauIrQgUxr9pPW6MbYipSu 0D93coMneMg4zcF+XKKkyGJSox+rZ+se0Ic8WwETYCqztkaeSYwcJIKFV8DvoHHvqCfU qbrmT3PDv3QpJiVHaNADDkg880qUVbhSBtov00h31JQgMlKPjlSd5GNzRlRzGZLT3jsn qzA8F/n5+J7wassztit+WyOCokOIiw5bHAl+766sY/gltBM8FK6f+r2Z2BggY+LXm+ua +vsiT7EOSeExKBPIfare/pgMf8sFr9EuPe/Lw82CPUqd9EF/2B4+9APNVbpwLCX9JsWs c4nQ== X-Gm-Message-State: AO0yUKVgDHOe6s6Oqee39X7PKqDfTh5rmF0voQ0aSyjO9kDiQ3vfvbR5 M5aSE7tTl3EfBxNlWSyZvx0= X-Google-Smtp-Source: AK7set+fXeYguHSdM/ECTto2wDq7Mo4z+CYXsMQV4PwwqbZd6DCt+5jTvUcB/xmS9G1k42Z3No87WA== X-Received: by 2002:a7b:c396:0:b0:3ee:19b4:a2e6 with SMTP id s22-20020a7bc396000000b003ee19b4a2e6mr5695693wmj.19.1679496935292; Wed, 22 Mar 2023 07:55:35 -0700 (PDT) Received: from lucifer.home ([2a00:23c5:dc8c:8701:1663:9a35:5a7b:1d76]) by smtp.googlemail.com with ESMTPSA id n23-20020a7bcbd7000000b003ed243222adsm16812246wmi.42.2023.03.22.07.55.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 22 Mar 2023 07:55:34 -0700 (PDT) From: Lorenzo Stoakes To: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Andrew Morton Cc: Baoquan He , Uladzislau Rezki , Matthew Wilcox , David Hildenbrand , Liu Shixin , Jiri Olsa , Jens Axboe , Alexander Viro , Lorenzo Stoakes Subject: [PATCH v6 2/4] fs/proc/kcore: convert read_kcore() to read_kcore_iter() Date: Wed, 22 Mar 2023 14:55:26 +0000 Message-Id: X-Mailer: git-send-email 2.39.2 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" For the time being we still use a bounce buffer for vread(), however in the next patch we will convert this to interact directly with the iterator and eliminate the bounce buffer altogether. Signed-off-by: Lorenzo Stoakes Reviewed-by: David Hildenbrand --- fs/proc/kcore.c | 36 ++++++++++++++++++------------------ 1 file changed, 18 insertions(+), 18 deletions(-) diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c index 556f310d6aa4..08b795fd80b4 100644 --- a/fs/proc/kcore.c +++ b/fs/proc/kcore.c @@ -24,7 +24,7 @@ #include #include #include -#include +#include #include #include #include @@ -308,9 +308,12 @@ static void append_kcore_note(char *notes, size_t *i, = const char *name, } =20 static ssize_t -read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *= fpos) +read_kcore_iter(struct kiocb *iocb, struct iov_iter *iter) { + struct file *file =3D iocb->ki_filp; char *buf =3D file->private_data; + loff_t *fpos =3D &iocb->ki_pos; + size_t phdrs_offset, notes_offset, data_offset; size_t page_offline_frozen =3D 1; size_t phdrs_len, notes_len; @@ -318,6 +321,7 @@ read_kcore(struct file *file, char __user *buffer, size= _t buflen, loff_t *fpos) size_t tsz; int nphdr; unsigned long start; + size_t buflen =3D iov_iter_count(iter); size_t orig_buflen =3D buflen; int ret =3D 0; =20 @@ -356,12 +360,11 @@ read_kcore(struct file *file, char __user *buffer, si= ze_t buflen, loff_t *fpos) }; =20 tsz =3D min_t(size_t, buflen, sizeof(struct elfhdr) - *fpos); - if (copy_to_user(buffer, (char *)&ehdr + *fpos, tsz)) { + if (copy_to_iter((char *)&ehdr + *fpos, tsz, iter) !=3D tsz) { ret =3D -EFAULT; goto out; } =20 - buffer +=3D tsz; buflen -=3D tsz; *fpos +=3D tsz; } @@ -398,15 +401,14 @@ read_kcore(struct file *file, char __user *buffer, si= ze_t buflen, loff_t *fpos) } =20 tsz =3D min_t(size_t, buflen, phdrs_offset + phdrs_len - *fpos); - if (copy_to_user(buffer, (char *)phdrs + *fpos - phdrs_offset, - tsz)) { + if (copy_to_iter((char *)phdrs + *fpos - phdrs_offset, tsz, + iter) !=3D tsz) { kfree(phdrs); ret =3D -EFAULT; goto out; } kfree(phdrs); =20 - buffer +=3D tsz; buflen -=3D tsz; *fpos +=3D tsz; } @@ -448,14 +450,13 @@ read_kcore(struct file *file, char __user *buffer, si= ze_t buflen, loff_t *fpos) min(vmcoreinfo_size, notes_len - i)); =20 tsz =3D min_t(size_t, buflen, notes_offset + notes_len - *fpos); - if (copy_to_user(buffer, notes + *fpos - notes_offset, tsz)) { + if (copy_to_iter(notes + *fpos - notes_offset, tsz, iter) !=3D tsz) { kfree(notes); ret =3D -EFAULT; goto out; } kfree(notes); =20 - buffer +=3D tsz; buflen -=3D tsz; *fpos +=3D tsz; } @@ -497,7 +498,7 @@ read_kcore(struct file *file, char __user *buffer, size= _t buflen, loff_t *fpos) } =20 if (!m) { - if (clear_user(buffer, tsz)) { + if (iov_iter_zero(tsz, iter) !=3D tsz) { ret =3D -EFAULT; goto out; } @@ -508,14 +509,14 @@ read_kcore(struct file *file, char __user *buffer, si= ze_t buflen, loff_t *fpos) case KCORE_VMALLOC: vread(buf, (char *)start, tsz); /* we have to zero-fill user buffer even if no read */ - if (copy_to_user(buffer, buf, tsz)) { + if (copy_to_iter(buf, tsz, iter) !=3D tsz) { ret =3D -EFAULT; goto out; } break; case KCORE_USER: /* User page is handled prior to normal kernel page: */ - if (copy_to_user(buffer, (char *)start, tsz)) { + if (copy_to_iter((char *)start, tsz, iter) !=3D tsz) { ret =3D -EFAULT; goto out; } @@ -531,7 +532,7 @@ read_kcore(struct file *file, char __user *buffer, size= _t buflen, loff_t *fpos) */ if (!page || PageOffline(page) || is_page_hwpoison(page) || !pfn_is_ram(pfn)) { - if (clear_user(buffer, tsz)) { + if (iov_iter_zero(tsz, iter) !=3D tsz) { ret =3D -EFAULT; goto out; } @@ -541,17 +542,17 @@ read_kcore(struct file *file, char __user *buffer, si= ze_t buflen, loff_t *fpos) case KCORE_VMEMMAP: case KCORE_TEXT: /* - * We use _copy_to_user() to bypass usermode hardening + * We use _copy_to_iter() to bypass usermode hardening * which would otherwise prevent this operation. */ - if (_copy_to_user(buffer, (char *)start, tsz)) { + if (_copy_to_iter((char *)start, tsz, iter) !=3D tsz) { ret =3D -EFAULT; goto out; } break; default: pr_warn_once("Unhandled KCORE type: %d\n", m->type); - if (clear_user(buffer, tsz)) { + if (iov_iter_zero(tsz, iter) !=3D tsz) { ret =3D -EFAULT; goto out; } @@ -559,7 +560,6 @@ read_kcore(struct file *file, char __user *buffer, size= _t buflen, loff_t *fpos) skip: buflen -=3D tsz; *fpos +=3D tsz; - buffer +=3D tsz; start +=3D tsz; tsz =3D (buflen > PAGE_SIZE ? PAGE_SIZE : buflen); } @@ -603,7 +603,7 @@ static int release_kcore(struct inode *inode, struct fi= le *file) } =20 static const struct proc_ops kcore_proc_ops =3D { - .proc_read =3D read_kcore, + .proc_read_iter =3D read_kcore_iter, .proc_open =3D open_kcore, .proc_release =3D release_kcore, .proc_lseek =3D default_llseek, --=20 2.39.2