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usb: usbmon: Read text within supplied buffer size

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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 2018-03-09 00:21:14 -06:00 committed by Greg Kroah-Hartman
parent 015dbeb228
commit a5f596830e
1 changed files with 84 additions and 54 deletions
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138
drivers/usb/mon/mon_text.c
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@ -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_read_t(struct file *file, char __user *buf,
size_t nbytes, loff_t *ppos)
static ssize_t mon_text_copy_to_user(struct mon_reader_text *rp,
char __user * const buf, const size_t nbytes)
{
struct mon_reader_text *rp = file->private_data;
struct mon_event_text *ep;
struct mon_text_ptr ptr;
const size_t togo = min(nbytes, rp->printf_togo);
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;
mutex_unlock(&rp->printf_lock);
kmem_cache_free(rp->e_slab, ep);
return ptr.cnt;
if (copy_to_user(buf, &rp->printf_buf[rp->printf_offset], togo))
return -EFAULT;
rp->printf_togo -= togo;
rp->printf_offset += togo;
return togo;
}
static ssize_t mon_text_read_u(struct file *file, char __user *buf,
size_t nbytes, loff_t *ppos)
/* 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)
{
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 {
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);
}
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;
}
/* 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)
{
struct mon_reader_text *rp = file->private_data;
struct mon_event_text *ep;
struct mon_text_ptr ptr;
ssize_t ret;
mutex_lock(&rp->printf_lock);
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);
}
ret = mon_text_copy_to_user(rp, buf, nbytes);
mutex_unlock(&rp->printf_lock);
return ret;
}
static struct mon_event_text *mon_text_read_wait(struct mon_reader_text *rp,