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authorGuus Sliepen <guus@sliepen.org>2009-07-22 17:39:42 +0200
committerGreg Kroah-Hartman <gregkh@suse.de>2009-09-23 06:46:30 -0700
commit665d7662d15441b4b3e54131a9418a1a198d0d31 (patch)
tree029c210e11d5f9befee6a51457a9dcd79b7934b6
parenta9d43091c5be1e7a60d5abe84be4f3050236b26a (diff)
USB: usbtmc: sanity checks for DEV_DEP_MSG_IN urbs
According to the specifications, an instrument should not return more data in a DEV_DEP_MSG_IN urb than requested. However, some instruments can send more than requested. This could cause the kernel to write the extra data past the end of the buffer provided by read(). Fix this by checking that the value of the TranserSize field is not larger than the urb itself and not larger than the size of the userspace buffer. Also correctly decrement the remaining size of the buffer when userspace read()s more than USBTMC_SIZE_IOBUFFER. Signed-off-by: Guus Sliepen <guus@sliepen.org> Cc: stable <stable@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--drivers/usb/class/usbtmc.c22
1 files changed, 18 insertions, 4 deletions
diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c
index 4f0858fbf98..5bab8e596c8 100644
--- a/drivers/usb/class/usbtmc.c
+++ b/drivers/usb/class/usbtmc.c
@@ -369,13 +369,13 @@ static ssize_t usbtmc_read(struct file *filp, char __user *buf,
{
struct usbtmc_device_data *data;
struct device *dev;
- unsigned long int n_characters;
+ u32 n_characters;
u8 *buffer;
int actual;
- int done;
- int remaining;
+ size_t done;
+ size_t remaining;
int retval;
- int this_part;
+ size_t this_part;
/* Get pointer to private data structure */
data = filp->private_data;
@@ -461,6 +461,18 @@ static ssize_t usbtmc_read(struct file *filp, char __user *buf,
(buffer[6] << 16) +
(buffer[7] << 24);
+ /* Ensure the instrument doesn't lie about it */
+ if(n_characters > actual - 12) {
+ dev_err(dev, "Device lies about message size: %zu > %zu\n", n_characters, actual - 12);
+ n_characters = actual - 12;
+ }
+
+ /* Ensure the instrument doesn't send more back than requested */
+ if(n_characters > this_part) {
+ dev_err(dev, "Device returns more than requested: %zu > %zu\n", done + n_characters, done + 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 */
@@ -471,6 +483,8 @@ static ssize_t usbtmc_read(struct file *filp, char __user *buf,
done += n_characters;
if (n_characters < USBTMC_SIZE_IOBUFFER)
remaining = 0;
+ else
+ remaining -= n_characters;
}
/* Update file position value */