Re: [syzbot] Re: [syzbot] [usb?] KMSAN: kernel-usb-infoleak in usbtmc_write

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Subject: Re: [syzbot] [usb?] KMSAN: kernel-usb-infoleak in usbtmc_write
Author: lizhi.xu@xxxxxxxxxxxxx

Short write.
User input data maybe invalid, clear the data buf of the user data before copying from user.

#syz test

diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c
index e9ddaa9b580d..b653bed40a13 100644
--- a/drivers/usb/class/usbtmc.c
+++ b/drivers/usb/class/usbtmc.c
@@ -1586,6 +1586,7 @@ static ssize_t usbtmc_write(struct file *filp, const char __user *buf,
 		aligned = (transfersize + (USBTMC_HEADER_SIZE + 3)) & ~3;
 	}
 
+	memset(&buffer[USBTMC_HEADER_SIZE], 0, transfersize);
 	if (copy_from_user(&buffer[USBTMC_HEADER_SIZE], buf, transfersize)) {
 		retval = -EFAULT;
 		up(&file_data->limit_write_sem);