[PATCH 4.4 67/70] mei: bus: type promotion bug in mei_nfc_if_version()

From: Greg Kroah-Hartman
Date: Mon Sep 24 2018 - 07:57:58 EST

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


From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

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@xxxxxxxxxxxxxxx>
Fixes: 582ab27a063a ("mei: bus: fix received data size check in NFC fixup")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Tomas Winkler <tomas.winkler@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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

--- a/drivers/misc/mei/bus-fixup.c
+++ b/drivers/misc/mei/bus-fixup.c
@@ -151,7 +151,7 @@ static int mei_nfc_if_version(struct mei

ret = 0;
bytes_recv = __mei_cl_recv(cl, (u8 *)reply, if_version_length);
- if (bytes_recv < 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;