From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753637AbeE3LeT (ORCPT ); Wed, 30 May 2018 07:34:19 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:60813 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752329AbeE3LHC (ORCPT ); Wed, 30 May 2018 07:07:02 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Greg Kroah-Hartman" , "Fredrik Noring" , "Pete Zaitcev" , "Pete Zaitcev" Date: Wed, 30 May 2018 11:52:41 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 121/153] usb: usbmon: Read text within supplied buffer size In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.102-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Pete Zaitcev commit a5f596830e27e15f7a0ecd6be55e433d776986d8 upstream. This change fixes buffer overflows and silent data corruption with the usbmon device driver text file read operations. Signed-off-by: Fredrik Noring Signed-off-by: Pete Zaitcev Signed-off-by: Greg Kroah-Hartman Signed-off-by: Ben Hutchings --- drivers/usb/mon/mon_text.c | 126 +++++++++++++++++++++++-------------- 1 file changed, 78 insertions(+), 48 deletions(-) --- a/drivers/usb/mon/mon_text.c +++ b/drivers/usb/mon/mon_text.c @@ -82,6 +82,8 @@ struct mon_reader_text { wait_queue_head_t wait; int printf_size; + size_t printf_offset; + size_t printf_togo; char *printf_buf; struct mutex printf_lock; @@ -373,75 +375,103 @@ err_alloc: return rc; } -/* - * For simplicity, we read one record in one system call and throw out - * what does not fit. This means that the following does not work: - * dd if=/dbg/usbmon/0t bs=10 - * Also, we do not allow seeks and do not bother advancing the offset. - */ +static ssize_t mon_text_copy_to_user(struct mon_reader_text *rp, + char __user * const buf, const size_t nbytes) +{ + const size_t togo = min(nbytes, rp->printf_togo); + + if (copy_to_user(buf, &rp->printf_buf[rp->printf_offset], togo)) + return -EFAULT; + rp->printf_togo -= togo; + rp->printf_offset += togo; + return togo; +} + +/* ppos is not advanced since the llseek operation is not permitted. */ static ssize_t mon_text_read_t(struct file *file, char __user *buf, - size_t nbytes, loff_t *ppos) + size_t nbytes, loff_t *ppos) { struct mon_reader_text *rp = file->private_data; struct mon_event_text *ep; struct mon_text_ptr ptr; + ssize_t ret; - ep = mon_text_read_wait(rp, file); - if (IS_ERR(ep)) - return PTR_ERR(ep); mutex_lock(&rp->printf_lock); - ptr.cnt = 0; - ptr.pbuf = rp->printf_buf; - ptr.limit = rp->printf_size; - - mon_text_read_head_t(rp, &ptr, ep); - mon_text_read_statset(rp, &ptr, ep); - ptr.cnt += snprintf(ptr.pbuf + ptr.cnt, ptr.limit - ptr.cnt, - " %d", ep->length); - mon_text_read_data(rp, &ptr, ep); - if (copy_to_user(buf, rp->printf_buf, ptr.cnt)) - ptr.cnt = -EFAULT; + if (rp->printf_togo == 0) { + + ep = mon_text_read_wait(rp, file); + if (IS_ERR(ep)) { + mutex_unlock(&rp->printf_lock); + return PTR_ERR(ep); + } + ptr.cnt = 0; + ptr.pbuf = rp->printf_buf; + ptr.limit = rp->printf_size; + + mon_text_read_head_t(rp, &ptr, ep); + mon_text_read_statset(rp, &ptr, ep); + ptr.cnt += snprintf(ptr.pbuf + ptr.cnt, ptr.limit - ptr.cnt, + " %d", ep->length); + mon_text_read_data(rp, &ptr, ep); + + rp->printf_togo = ptr.cnt; + rp->printf_offset = 0; + + kmem_cache_free(rp->e_slab, ep); + } + + ret = mon_text_copy_to_user(rp, buf, nbytes); mutex_unlock(&rp->printf_lock); - kmem_cache_free(rp->e_slab, ep); - return ptr.cnt; + return ret; } +/* ppos is not advanced since the llseek operation is not permitted. */ static ssize_t mon_text_read_u(struct file *file, char __user *buf, - size_t nbytes, loff_t *ppos) + size_t nbytes, loff_t *ppos) { struct mon_reader_text *rp = file->private_data; struct mon_event_text *ep; struct mon_text_ptr ptr; + ssize_t ret; - ep = mon_text_read_wait(rp, file); - if (IS_ERR(ep)) - return PTR_ERR(ep); mutex_lock(&rp->printf_lock); - ptr.cnt = 0; - ptr.pbuf = rp->printf_buf; - ptr.limit = rp->printf_size; - mon_text_read_head_u(rp, &ptr, ep); - if (ep->type == 'E') { - mon_text_read_statset(rp, &ptr, ep); - } else if (ep->xfertype == USB_ENDPOINT_XFER_ISOC) { - mon_text_read_isostat(rp, &ptr, ep); - mon_text_read_isodesc(rp, &ptr, ep); - } else if (ep->xfertype == USB_ENDPOINT_XFER_INT) { - mon_text_read_intstat(rp, &ptr, ep); - } else { - mon_text_read_statset(rp, &ptr, ep); + if (rp->printf_togo == 0) { + + ep = mon_text_read_wait(rp, file); + if (IS_ERR(ep)) { + mutex_unlock(&rp->printf_lock); + return PTR_ERR(ep); + } + ptr.cnt = 0; + ptr.pbuf = rp->printf_buf; + ptr.limit = rp->printf_size; + + mon_text_read_head_u(rp, &ptr, ep); + if (ep->type == 'E') { + mon_text_read_statset(rp, &ptr, ep); + } else if (ep->xfertype == USB_ENDPOINT_XFER_ISOC) { + mon_text_read_isostat(rp, &ptr, ep); + mon_text_read_isodesc(rp, &ptr, ep); + } else if (ep->xfertype == USB_ENDPOINT_XFER_INT) { + mon_text_read_intstat(rp, &ptr, ep); + } else { + mon_text_read_statset(rp, &ptr, ep); + } + ptr.cnt += snprintf(ptr.pbuf + ptr.cnt, ptr.limit - ptr.cnt, + " %d", ep->length); + mon_text_read_data(rp, &ptr, ep); + + rp->printf_togo = ptr.cnt; + rp->printf_offset = 0; + + kmem_cache_free(rp->e_slab, ep); } - ptr.cnt += snprintf(ptr.pbuf + ptr.cnt, ptr.limit - ptr.cnt, - " %d", ep->length); - mon_text_read_data(rp, &ptr, ep); - if (copy_to_user(buf, rp->printf_buf, ptr.cnt)) - ptr.cnt = -EFAULT; + ret = mon_text_copy_to_user(rp, buf, nbytes); mutex_unlock(&rp->printf_lock); - kmem_cache_free(rp->e_slab, ep); - return ptr.cnt; + return ret; } static struct mon_event_text *mon_text_read_wait(struct mon_reader_text *rp,