From 1d44f7f5bc07127743e9d4a4f968bcbaf3b95ee9 Mon Sep 17 00:00:00 2001 From: Ben Hutchings Date: Wed, 15 Aug 2018 21:45:37 +0100 Subject: USB: yurex: Check for truncation in yurex_read() [ Upstream commit 14427b86837a4baf1c121934c6599bdb67dfa9fc ] snprintf() always returns the full length of the string it could have printed, even if it was truncated because the buffer was too small. So in case the counter value is truncated, we will over-read from in_buffer and over-write to the caller's buffer. I don't think it's actually possible for this to happen, but in case truncation occurs, WARN and return -EIO. Signed-off-by: Ben Hutchings Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/usb/misc/yurex.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'drivers/usb') diff --git a/drivers/usb/misc/yurex.c b/drivers/usb/misc/yurex.c index 1232dd49556d..6d9fd5f64903 100644 --- a/drivers/usb/misc/yurex.c +++ b/drivers/usb/misc/yurex.c @@ -413,6 +413,9 @@ static ssize_t yurex_read(struct file *file, char __user *buffer, size_t count, spin_unlock_irqrestore(&dev->lock, flags); mutex_unlock(&dev->io_mutex); + if (WARN_ON_ONCE(len >= sizeof(in_buffer))) + return -EIO; + return simple_read_from_buffer(buffer, count, ppos, in_buffer, len); } -- cgit v1.2.3