From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f196.google.com ([209.85.192.196]:34555 "EHLO mail-pf0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934742AbeGFTct (ORCPT ); Fri, 6 Jul 2018 15:32:49 -0400 Received: by mail-pf0-f196.google.com with SMTP id e10-v6so9187277pfn.1 for ; Fri, 06 Jul 2018 12:32:49 -0700 (PDT) From: Omar Sandoval To: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Alexey Dobriyan Cc: Eric Biederman , kernel-team@fb.com Subject: [PATCH 4/7] proc/kcore: hold lock during read Date: Fri, 6 Jul 2018 12:32:35 -0700 Message-Id: <974fd58d9eb5eb536a2b6b5580137ee567864c32.1530904769.git.osandov@fb.com> In-Reply-To: References: Sender: linux-fsdevel-owner@vger.kernel.org List-ID: From: Omar Sandoval Now that we're using an rwsem, we can hold it during the entirety of read_kcore() and have a common return path. This is preparation for the next change. Signed-off-by: Omar Sandoval --- fs/proc/kcore.c | 70 ++++++++++++++++++++++++++++--------------------- 1 file changed, 40 insertions(+), 30 deletions(-) diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c index f335400300d3..b7ff2e2ec350 100644 --- a/fs/proc/kcore.c +++ b/fs/proc/kcore.c @@ -438,19 +438,18 @@ static ssize_t read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) { char *buf = file->private_data; - ssize_t acc = 0; size_t size, tsz; size_t elf_buflen; int nphdr; unsigned long start; + size_t orig_buflen = buflen; + int ret = 0; down_read(&kclist_lock); size = get_kcore_size(&nphdr, &elf_buflen); - if (buflen == 0 || *fpos >= size) { - up_read(&kclist_lock); - return 0; - } + if (buflen == 0 || *fpos >= size) + goto out; /* trim buflen to not go beyond EOF */ if (buflen > size - *fpos) @@ -463,28 +462,26 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) tsz = elf_buflen - *fpos; if (buflen < tsz) tsz = buflen; - elf_buf = kzalloc(elf_buflen, GFP_ATOMIC); + elf_buf = kzalloc(elf_buflen, GFP_KERNEL); if (!elf_buf) { - up_read(&kclist_lock); - return -ENOMEM; + ret = -ENOMEM; + goto out; } elf_kcore_store_hdr(elf_buf, nphdr, elf_buflen); - up_read(&kclist_lock); if (copy_to_user(buffer, elf_buf + *fpos, tsz)) { kfree(elf_buf); - return -EFAULT; + ret = -EFAULT; + goto out; } kfree(elf_buf); buflen -= tsz; *fpos += tsz; buffer += tsz; - acc += tsz; /* leave now if filled buffer already */ if (buflen == 0) - return acc; - } else - up_read(&kclist_lock); + goto out; + } /* * Check to see if our file offset matches with any of @@ -497,25 +494,29 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) while (buflen) { struct kcore_list *m; - down_read(&kclist_lock); list_for_each_entry(m, &kclist_head, list) { if (start >= m->addr && start < (m->addr+m->size)) break; } - up_read(&kclist_lock); if (&m->list == &kclist_head) { - if (clear_user(buffer, tsz)) - return -EFAULT; + if (clear_user(buffer, tsz)) { + ret = -EFAULT; + goto out; + } } else if (m->type == 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)) - return -EFAULT; + if (copy_to_user(buffer, buf, tsz)) { + ret = -EFAULT; + goto out; + } } else if (m->type == KCORE_USER) { /* User page is handled prior to normal kernel page: */ - if (copy_to_user(buffer, (char *)start, tsz)) - return -EFAULT; + if (copy_to_user(buffer, (char *)start, tsz)) { + ret = -EFAULT; + goto out; + } } else { if (kern_addr_valid(start)) { /* @@ -523,26 +524,35 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) * hardened user copy kernel text checks. */ if (probe_kernel_read(buf, (void *) start, tsz)) { - if (clear_user(buffer, tsz)) - return -EFAULT; + if (clear_user(buffer, tsz)) { + ret = -EFAULT; + goto out; + } } else { - if (copy_to_user(buffer, buf, tsz)) - return -EFAULT; + if (copy_to_user(buffer, buf, tsz)) { + ret = -EFAULT; + goto out; + } } } else { - if (clear_user(buffer, tsz)) - return -EFAULT; + if (clear_user(buffer, tsz)) { + ret = -EFAULT; + goto out; + } } } buflen -= tsz; *fpos += tsz; buffer += tsz; - acc += tsz; start += tsz; tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen); } - return acc; +out: + up_write(&kclist_lock); + if (ret) + return ret; + return orig_buflen - buflen; } -- 2.18.0