From 127af8828518074ab24e9b5678229513d198d832 Mon Sep 17 00:00:00 2001 From: Eli Billauer Date: Fri, 27 Mar 2015 11:56:06 +0300 Subject: [PATCH] char: xillybus: Don't return -EFAULT on user-triggered flush The API allows the application to flush a host-to-FPGA stream by calling write() with the data count set to zero. Before this patch, copy_from_user() was called with a non-zero byte count, which possibly made it attempt to read from unmapped user memory. Such attempts caused the driver to return -EFAULT instead of 0, even though the desired operation went through fine. This patch ensures the driver returns 0 on a successful flush. Signed-off-by: Eli Billauer Signed-off-by: Greg Kroah-Hartman --- drivers/char/xillybus/xillybus_core.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/char/xillybus/xillybus_core.c b/drivers/char/xillybus/xillybus_core.c index b827fa095f1b..77d6c127e691 100644 --- a/drivers/char/xillybus/xillybus_core.c +++ b/drivers/char/xillybus/xillybus_core.c @@ -1237,6 +1237,8 @@ static ssize_t xillybus_write(struct file *filp, const char __user *userbuf, unsigned char *tail; int i; + howmany = 0; + end_offset_plus1 = bufpos >> channel->log2_element_size;