linux-kernel - [PATCH 5.4 244/340] media: mceusb: Fix potential out-of-bounds shift

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Message-Id: <20210301161100.297368594@linuxfoundation.org>
Date:   Mon,  1 Mar 2021 17:13:08 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        syzbot+ec3b3128c576e109171d@...kaller.appspotmail.com,
        James Reynolds <jr@...len.com>, Sean Young <sean@...s.org>,
        Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Subject: [PATCH 5.4 244/340] media: mceusb: Fix potential out-of-bounds shift

From: James Reynolds <jr@...len.com>

commit 1b43bad31fb0e00f45baf5b05bd21eb8d8ce7f58 upstream.

When processing a MCE_RSP_GETPORTSTATUS command, the bit index to set in
ir->txports_cabled comes from response data, and isn't validated.

As ir->txports_cabled is a u8, nothing should be done if the bit index
is greater than 7.

Cc: stable@...r.kernel.org
Reported-by: syzbot+ec3b3128c576e109171d@...kaller.appspotmail.com
Signed-off-by: James Reynolds <jr@...len.com>
Signed-off-by: Sean Young <sean@...s.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/media/rc/mceusb.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/media/rc/mceusb.c
+++ b/drivers/media/rc/mceusb.c
@@ -1169,7 +1169,7 @@ static void mceusb_handle_command(struct
 		switch (subcmd) {
 		/* the one and only 5-byte return value command */
 		case MCE_RSP_GETPORTSTATUS:
-			if (buf_in[5] == 0)
+			if (buf_in[5] == 0 && *hi < 8)
 				ir->txports_cabled |= 1 << *hi;
 			break;