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

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Message-Id: <20180711122932.28197-3-tomas.winkler@intel.com>
Date:   Wed, 11 Jul 2018 15:29:32 +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,
        Tomas Winkler <tomas.winkler@...el.com>,
        Dan Carpenter <dan.carpenter@...cle.com>
Subject: [char-misc-next 2/2] mei: bus: type promotion bug in mei_fwver()

if __mei_cl_recv() returns a negative then "bytes_recv"
type is promoted to a high positive value in comparison with
size_t evaluated by MKHI_FWVER_LEN(1). It results in error condition
not to be detected.

Cc: Dan Carpenter <dan.carpenter@...cle.com>
Fixes: 9078ad92ef86 ("mei: expose fw version to sysfs")
Signed-off-by: Tomas Winkler <tomas.winkler@...el.com>
---
 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 65e28be3c8cc..4c232f0eae90 100644
--- a/drivers/misc/mei/bus-fixup.c
+++ b/drivers/misc/mei/bus-fixup.c
@@ -181,7 +181,7 @@ static int mei_fwver(struct mei_cl_device *cldev)
 	ret = 0;
 	bytes_recv = __mei_cl_recv(cldev->cl, buf, sizeof(buf), 0,
 				   MKHI_RCV_TIMEOUT);
-	if (bytes_recv < MKHI_FWVER_LEN(1)) {
+	if (bytes_recv < 0 || bytes_recv < MKHI_FWVER_LEN(1)) {
 		/*
 		 * Should be at least one version block,
 		 * error out if nothing found
-- 
2.14.4