From 37188559c610f1b7eec83c8e448936c361c578de Mon Sep 17 00:00:00 2001
From: Yu Kuai <yukuai3@huawei.com>
Date: Fri, 21 May 2021 20:06:17 +0800
Subject: [PATCH] char: pcmcia: error out if 'num_bytes_read' is greater than 4 in set_protocol()
Git-commit: 37188559c610f1b7eec83c8e448936c361c578de
Patch-mainline: v5.14-rc1
References: git-fixes

Theoretically, it will cause index out of bounds error if
'num_bytes_read' is greater than 4. As we expect it(and was tested)
never to be greater than 4, error out if it happens.

Fixes: c1986ee9bea3 ("[PATCH] New Omnikey Cardman 4000 driver")
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20210521120617.138396-1-yukuai3@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/char/pcmcia/cm4000_cs.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/char/pcmcia/cm4000_cs.c
+++ b/drivers/char/pcmcia/cm4000_cs.c
@@ -544,6 +544,10 @@ static int set_protocol(struct cm4000_de
 		io_read_num_rec_bytes(iobase, &num_bytes_read);
 		if (num_bytes_read >= 4) {
 			DEBUGP(2, dev, "NumRecBytes = %i\n", num_bytes_read);
+			if (num_bytes_read > 4) {
+				rc = -EIO;
+				goto exit_setprotocol;
+			}
 			break;
 		}
 		mdelay(10);