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USB: yurex: Fix buffer over-read in yurex_write() 

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.

Cc: stable@vger.kernel.org
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ben Hutchings 2018-08-15 21:44:25 +01:00 committed by Greg Kroah-Hartman
parent 222471f764
commit 7e10f14ebf
1 changed files with 3 additions and 2 deletions
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5
drivers/usb/misc/yurex.c
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@ -421,13 +421,13 @@ static ssize_t yurex_write(struct file *file, const char __user *user_buffer,
{
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 = file->private_data;
/* verify that we actually have some data to write */
@ -446,6 +446,7 @@ static ssize_t yurex_write(struct file *file, const char __user *user_buffer,
retval = -EFAULT;
goto error;
}
buffer[count] = 0;
memset(dev->cntl_buffer, CMD_PADDING, YUREX_BUF_SIZE);
switch (buffer[0]) {