linux-kernel - [char-misc-next v2 1/2] mei: bus: type promotion bug in mei_nfc_if

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Message-Id: <20180711122932.28197-2-tomas.winkler@intel.com>
Date:   Wed, 11 Jul 2018 15:29:31 +0300
From:   Tomas Winkler <tomas.winkler@...el.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Alexander Usyskin <alexander.usyskin@...el.com>,
        linux-kernel@...r.kernel.org,
        Dan Carpenter <dan.carpenter@...cle.com>,
        stable@...r.kernel.org, Tomas Winkler <tomas.winkler@...el.com>
Subject: [char-misc-next v2 1/2] mei: bus: type promotion bug in mei_nfc_if_version()

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

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>
---
V2: rebase
 drivers/misc/mei/bus-fixup.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/misc/mei/bus-fixup.c b/drivers/misc/mei/bus-fixup.c
index e45fe826d87d..65e28be3c8cc 100644
--- a/drivers/misc/mei/bus-fixup.c
+++ b/drivers/misc/mei/bus-fixup.c
@@ -341,7 +341,7 @@ static int mei_nfc_if_version(struct mei_cl *cl,
 
 	ret = 0;
 	bytes_recv = __mei_cl_recv(cl, (u8 *)reply, if_version_length, 0, 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;
-- 
2.14.4