[PATCH 3.16 192/306] mei: bus: fix received data size check in NFC fixup

From: Ben Hutchings
Date: Wed Feb 15 2017 - 18:10:22 EST

3.16.40-rc1 review patch. If anyone has any objections, please let me know.


From: Alexander Usyskin <alexander.usyskin@xxxxxxxxx>

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

Fixes: 59fcd7c63abf (mei: nfc: Initial nfc implementation)
Signed-off-by: Alexander Usyskin <alexander.usyskin@xxxxxxxxx>
Signed-off-by: Tomas Winkler <tomas.winkler@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
[bwh: Backported to 3.16:
- Drop change in mei_phy.c
- Adjust filename]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
--- a/drivers/misc/mei/nfc.c
+++ b/drivers/misc/mei/nfc.c
@@ -292,7 +292,7 @@ static int mei_nfc_if_version(struct mei
return -ENOMEM;

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(&dev->pdev->dev, "Could not read IF version\n");
ret = -EIO;
goto err;