linux-kernel - [PATCH 4.8 61/92] mei: bus: fix received data size check in NFC fixup

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Date:   Thu, 17 Nov 2016 11:32:34 +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,
        Alexander Usyskin <alexander.usyskin@...el.com>,
        Tomas Winkler <tomas.winkler@...el.com>
Subject: [PATCH 4.8 61/92] mei: bus: fix received data size check in NFC fixup

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

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

From: Alexander Usyskin <alexander.usyskin@...el.com>

commit 582ab27a063a506ccb55fc48afcc325342a2deba upstream.

NFC version reply size checked against only header size, not against
full message size. That may lead potentially to uninitialized memory access
in version data.

That leads to warnings when version data is accessed:
drivers/misc/mei/bus-fixup.c: warning: '*((void *)&ver+11)' may be used uninitialized in this function [-Wuninitialized]:  => 212:2

Reported in
Build regressions/improvements in v4.9-rc3
https://lkml.org/lkml/2016/10/30/57

Fixes: 59fcd7c63abf (mei: nfc: Initial nfc implementation)
Signed-off-by: Alexander Usyskin <alexander.usyskin@...el.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 +-
 drivers/nfc/mei_phy.c        |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

--- 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
 
 	ret = 0;
 	bytes_recv = __mei_cl_recv(cl, (u8 *)reply, if_version_length);
-	if (bytes_recv < 0 || bytes_recv < sizeof(struct mei_nfc_reply)) {
+	if (bytes_recv < if_version_length) {
 		dev_err(bus->dev, "Could not read IF version\n");
 		ret = -EIO;
 		goto err;
--- a/drivers/nfc/mei_phy.c
+++ b/drivers/nfc/mei_phy.c
@@ -133,7 +133,7 @@ static int mei_nfc_if_version(struct nfc
 		return -ENOMEM;
 
 	bytes_recv = mei_cldev_recv(phy->cldev, (u8 *)reply, if_version_length);
-	if (bytes_recv < 0 || bytes_recv < sizeof(struct mei_nfc_reply)) {
+	if (bytes_recv < 0 || bytes_recv < if_version_length) {
 		pr_err("Could not read IF version\n");
 		r = -EIO;
 		goto err;