[PATCH 4.18 220/235] drm/panel: type promotion bug in s6e8aa0_read_mtp_id()

From: Greg Kroah-Hartman
Date: Mon Sep 24 2018 - 08:47:13 EST


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

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

From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

[ Upstream commit cd0e0ca69109d025b1a1b6609f70682db62138b0 ]

The ARRAY_SIZE() macro is type size_t. If s6e8aa0_dcs_read() returns a
negative error code, then "ret < ARRAY_SIZE(id)" is false because the
negative error code is type promoted to a high positive value.

Fixes: 02051ca06371 ("drm/panel: add S6E8AA0 driver")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Reviewed-by: Andrzej Hajda <a.hajda@xxxxxxxxxxx>
Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20180704093807.s3lqsb2v6dg2k43d@xxxxxxxxxxxxx
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/panel/panel-samsung-s6e8aa0.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/gpu/drm/panel/panel-samsung-s6e8aa0.c
+++ b/drivers/gpu/drm/panel/panel-samsung-s6e8aa0.c
@@ -823,7 +823,7 @@ static void s6e8aa0_read_mtp_id(struct s
int ret, i;

ret = s6e8aa0_dcs_read(ctx, 0xd1, id, ARRAY_SIZE(id));
- if (ret < ARRAY_SIZE(id) || id[0] == 0x00) {
+ if (ret < 0 || ret < ARRAY_SIZE(id) || id[0] == 0x00) {
dev_err(ctx->dev, "read id failed\n");
ctx->error = -EIO;
return;