linux-kernel - [char-misc v4.9.y] mei: bus: type promotion bug in mei_nfc_if

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Message-Id: <20180923050951.29018-1-tomas.winkler@intel.com>
Date:   Sun, 23 Sep 2018 08:09:51 +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, stable@...r.kernel.org,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Tomas Winkler <tomas.winkler@...el.com>
Subject: [char-misc v4.9.y] mei: bus: type promotion bug in mei_nfc_if_version()

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> # 4.9
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(-)

diff --git a/drivers/misc/mei/bus-fixup.c b/drivers/misc/mei/bus-fixup.c
index 75b9d4ac8b1e..371f5f66a9d6 100644
--- a/drivers/misc/mei/bus-fixup.c
+++ b/drivers/misc/mei/bus-fixup.c
@@ -178,7 +178,7 @@ static int mei_nfc_if_version(struct mei_cl *cl,
 
 	ret = 0;
 	bytes_recv = __mei_cl_recv(cl, (u8 *)reply, if_version_length);
-	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