USB: usbtmc: inhibit corruption

Limit data copied to userspace to amount requested.  Prevents a faulty
instrument from overwriting user memory.

Signed-off-by: Steve Holland <sdh4@iastate.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c
index f2fde7cd6109..91d3a94eeaa0 100644
--- a/drivers/usb/class/usbtmc.c
+++ b/drivers/usb/class/usbtmc.c
@@ -473,6 +473,10 @@ static ssize_t usbtmc_read(struct file *filp, char __user *buf,
                         n_characters = this_part;
                 }
 
+                /* Bound amount of data received by amount of data requested */
+                if (n_characters > this_part)
+                        n_characters = this_part;
+
                 /* Copy buffer to user space */
                 if (copy_to_user(buf + done, &buffer[12], n_characters)) {
                         /* There must have been an addressing problem */