usb: usbmon: Read text within supplied buffer size
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>
This commit is contained in:
Pete Zaitcev
Greg Kroah-Hartman
parent
015dbeb228
commit
a5f596830e
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@ -85,6 +85,8 @@ struct mon_reader_text {
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wait_queue_head_t wait;
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int printf_size;
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size_t printf_offset;
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size_t printf_togo;
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char *printf_buf;
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struct mutex printf_lock;
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@ -376,75 +378,103 @@ err_alloc:
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return rc;
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}
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/*
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* For simplicity, we read one record in one system call and throw out
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* what does not fit. This means that the following does not work:
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* dd if=/dbg/usbmon/0t bs=10
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* Also, we do not allow seeks and do not bother advancing the offset.
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*/
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static ssize_t mon_text_read_t(struct file *file, char __user *buf,
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size_t nbytes, loff_t *ppos)
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static ssize_t mon_text_copy_to_user(struct mon_reader_text *rp,
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char __user * const buf, const size_t nbytes)
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{
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struct mon_reader_text *rp = file->private_data;
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struct mon_event_text *ep;
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struct mon_text_ptr ptr;
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const size_t togo = min(nbytes, rp->printf_togo);
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ep = mon_text_read_wait(rp, file);
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if (IS_ERR(ep))
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return PTR_ERR(ep);
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mutex_lock(&rp->printf_lock);
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ptr.cnt = 0;
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ptr.pbuf = rp->printf_buf;
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ptr.limit = rp->printf_size;
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mon_text_read_head_t(rp, &ptr, ep);
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mon_text_read_statset(rp, &ptr, ep);
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ptr.cnt += snprintf(ptr.pbuf + ptr.cnt, ptr.limit - ptr.cnt,
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" %d", ep->length);
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mon_text_read_data(rp, &ptr, ep);
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if (copy_to_user(buf, rp->printf_buf, ptr.cnt))
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ptr.cnt = -EFAULT;
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mutex_unlock(&rp->printf_lock);
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kmem_cache_free(rp->e_slab, ep);
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return ptr.cnt;
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if (copy_to_user(buf, &rp->printf_buf[rp->printf_offset], togo))
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return -EFAULT;
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rp->printf_togo -= togo;
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rp->printf_offset += togo;
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return togo;
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}
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static ssize_t mon_text_read_u(struct file *file, char __user *buf,
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size_t nbytes, loff_t *ppos)
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/* ppos is not advanced since the llseek operation is not permitted. */
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static ssize_t mon_text_read_t(struct file *file, char __user *buf,
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size_t nbytes, loff_t *ppos)
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{
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struct mon_reader_text *rp = file->private_data;
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struct mon_event_text *ep;
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struct mon_text_ptr ptr;
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ssize_t ret;
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ep = mon_text_read_wait(rp, file);
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if (IS_ERR(ep))
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return PTR_ERR(ep);
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mutex_lock(&rp->printf_lock);
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ptr.cnt = 0;
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ptr.pbuf = rp->printf_buf;
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ptr.limit = rp->printf_size;
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mon_text_read_head_u(rp, &ptr, ep);
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if (ep->type == 'E') {
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mon_text_read_statset(rp, &ptr, ep);
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} else if (ep->xfertype == USB_ENDPOINT_XFER_ISOC) {
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mon_text_read_isostat(rp, &ptr, ep);
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mon_text_read_isodesc(rp, &ptr, ep);
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} else if (ep->xfertype == USB_ENDPOINT_XFER_INT) {
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mon_text_read_intstat(rp, &ptr, ep);
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} else {
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if (rp->printf_togo == 0) {
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ep = mon_text_read_wait(rp, file);
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if (IS_ERR(ep)) {
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mutex_unlock(&rp->printf_lock);
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return PTR_ERR(ep);
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}
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ptr.cnt = 0;
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ptr.pbuf = rp->printf_buf;
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ptr.limit = rp->printf_size;
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mon_text_read_head_t(rp, &ptr, ep);
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mon_text_read_statset(rp, &ptr, ep);
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ptr.cnt += snprintf(ptr.pbuf + ptr.cnt, ptr.limit - ptr.cnt,
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" %d", ep->length);
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mon_text_read_data(rp, &ptr, ep);
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rp->printf_togo = ptr.cnt;
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rp->printf_offset = 0;
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kmem_cache_free(rp->e_slab, ep);
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}
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ptr.cnt += snprintf(ptr.pbuf + ptr.cnt, ptr.limit - ptr.cnt,
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" %d", ep->length);
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mon_text_read_data(rp, &ptr, ep);
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if (copy_to_user(buf, rp->printf_buf, ptr.cnt))
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ptr.cnt = -EFAULT;
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ret = mon_text_copy_to_user(rp, buf, nbytes);
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mutex_unlock(&rp->printf_lock);
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kmem_cache_free(rp->e_slab, ep);
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return ptr.cnt;
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return ret;
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}
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/* ppos is not advanced since the llseek operation is not permitted. */
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static ssize_t mon_text_read_u(struct file *file, char __user *buf,
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size_t nbytes, loff_t *ppos)
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{
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struct mon_reader_text *rp = file->private_data;
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struct mon_event_text *ep;
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struct mon_text_ptr ptr;
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ssize_t ret;
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mutex_lock(&rp->printf_lock);
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if (rp->printf_togo == 0) {
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ep = mon_text_read_wait(rp, file);
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if (IS_ERR(ep)) {
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mutex_unlock(&rp->printf_lock);
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return PTR_ERR(ep);
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}
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ptr.cnt = 0;
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ptr.pbuf = rp->printf_buf;
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ptr.limit = rp->printf_size;
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mon_text_read_head_u(rp, &ptr, ep);
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if (ep->type == 'E') {
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mon_text_read_statset(rp, &ptr, ep);
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} else if (ep->xfertype == USB_ENDPOINT_XFER_ISOC) {
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mon_text_read_isostat(rp, &ptr, ep);
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mon_text_read_isodesc(rp, &ptr, ep);
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} else if (ep->xfertype == USB_ENDPOINT_XFER_INT) {
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mon_text_read_intstat(rp, &ptr, ep);
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} else {
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mon_text_read_statset(rp, &ptr, ep);
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}
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ptr.cnt += snprintf(ptr.pbuf + ptr.cnt, ptr.limit - ptr.cnt,
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" %d", ep->length);
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mon_text_read_data(rp, &ptr, ep);
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rp->printf_togo = ptr.cnt;
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rp->printf_offset = 0;
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kmem_cache_free(rp->e_slab, ep);
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}
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ret = mon_text_copy_to_user(rp, buf, nbytes);
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mutex_unlock(&rp->printf_lock);
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return ret;
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}
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static struct mon_event_text *mon_text_read_wait(struct mon_reader_text *rp,
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