| From: Ben Hutchings <ben.hutchings@codethink.co.uk> |
| Date: Wed, 15 Aug 2018 21:44:25 +0100 |
| Subject: USB: yurex: Fix buffer over-read in yurex_write() |
| |
| commit 7e10f14ebface44a48275c8d6dc1caae3668d5a9 upstream. |
| |
| If the written data starts with a digit, yurex_write() tries to parse |
| it as an integer using simple_strtoull(). This requires a null- |
| terminator, and currently there's no guarantee that there is one. |
| |
| (The sample program at |
| https://github.com/NeoCat/YUREX-driver-for-Linux/blob/master/sample/yurex_clock.pl |
| writes an integer without a null terminator. It seems like it must |
| have worked by chance!) |
| |
| Always add a null byte after the written data. Enlarge the buffer |
| to allow for this. |
| |
| Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| [bwh: Backported to 3.16: adjust context] |
| Signed-off-by: Ben Hutchings <ben@decadent.org.uk> |
| --- |
| drivers/usb/misc/yurex.c | 5 +++-- |
| 1 file changed, 3 insertions(+), 2 deletions(-) |
| |
| --- a/drivers/usb/misc/yurex.c |
| +++ b/drivers/usb/misc/yurex.c |
| @@ -437,13 +437,13 @@ static ssize_t yurex_write(struct file * |
| { |
| struct usb_yurex *dev; |
| int i, set = 0, retval = 0; |
| - char buffer[16]; |
| + char buffer[16 + 1]; |
| char *data = buffer; |
| unsigned long long c, c2 = 0; |
| signed long timeout = 0; |
| DEFINE_WAIT(wait); |
| |
| - count = min(sizeof(buffer), count); |
| + count = min(sizeof(buffer) - 1, count); |
| dev = (struct usb_yurex *)file->private_data; |
| |
| /* verify that we actually have some data to write */ |
| @@ -462,6 +462,7 @@ static ssize_t yurex_write(struct file * |
| retval = -EFAULT; |
| goto error; |
| } |
| + buffer[count] = 0; |
| memset(dev->cntl_buffer, CMD_PADDING, YUREX_BUF_SIZE); |
| |
| switch (buffer[0]) { |
