4.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Pete Zaitcev zaitcev@kotori.zaitcev.us
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 noring@nocrew.org Signed-off-by: Pete Zaitcev zaitcev@redhat.com Cc: stable stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/usb/mon/mon_text.c | 124 +++++++++++++++++++++++++++------------------ 1 file changed, 77 insertions(+), 47 deletions(-)
--- a/drivers/usb/mon/mon_text.c +++ b/drivers/usb/mon/mon_text.c @@ -85,6 +85,8 @@ 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;
@@ -376,75 +378,103 @@ 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,