usb: iowarrior: don't trust report_size for buffer size

If the iowarrior devices in this case statement support more than 8 bytes
per report, it is possible to write past the end of a kernel heap allocation.
This will probably never be possible, but change the allocation to be more
defensive anyway.

Signed-off-by: Kees Cook <kees.cook@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/misc/iowarrior.c b/drivers/usb/misc/iowarrior.c
index bc88c79875a146712cae5fcb7461325501f20ad7..8ed8d05750d42a587599b97c803e81eb4998cc84 100644 (file)
--- a/drivers/usb/misc/iowarrior.c
+++ b/drivers/usb/misc/iowarrior.c
@@ -374,7 +374,7 @@ static ssize_t iowarrior_write(struct file *file,
        case USB_DEVICE_ID_CODEMERCS_IOWPV2:
        case USB_DEVICE_ID_CODEMERCS_IOW40:
                /* IOW24 and IOW40 use a synchronous call */
-               buf = kmalloc(8, GFP_KERNEL);   /* 8 bytes are enough for both products */
+               buf = kmalloc(count, GFP_KERNEL);
                if (!buf) {
                        retval = -ENOMEM;
                        goto exit;