linux-kernel - [PATCH 4.18 234/235] mei: bus: type promotion bug in mei_nfc_if

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Message-Id: <20180924113126.113229959@linuxfoundation.org>
Date:   Mon, 24 Sep 2018 13:53:40 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Dan Carpenter <dan.carpenter@...cle.com>,
        Tomas Winkler <tomas.winkler@...el.com>
Subject: [PATCH 4.18 234/235] mei: bus: type promotion bug in mei_nfc_if_version()

4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Carpenter <dan.carpenter@...cle.com>

commit b40b3e9358fbafff6a4ba0f4b9658f6617146f9c upstream.

We accidentally removed the check for negative returns
without considering the issue of type promotion.
The "if_version_length" variable is type size_t so if __mei_cl_recv()
returns a negative then "bytes_recv" is type promoted
to a high positive value and treated as success.

Cc: <stable@...r.kernel.org>
Fixes: 582ab27a063a ("mei: bus: fix received data size check in NFC fixup")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Tomas Winkler <tomas.winkler@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>


---
 drivers/misc/mei/bus-fixup.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/misc/mei/bus-fixup.c
+++ b/drivers/misc/mei/bus-fixup.c
@@ -267,7 +267,7 @@ static int mei_nfc_if_version(struct mei
 
 	ret = 0;
 	bytes_recv = __mei_cl_recv(cl, (u8 *)reply, if_version_length, 0);
-	if (bytes_recv < if_version_length) {
+	if (bytes_recv < 0 || bytes_recv < if_version_length) {
 		dev_err(bus->dev, "Could not read IF version\n");
 		ret = -EIO;
 		goto err;