[PATCH 4.17 012/324] drm/bridge/sii8620: fix potential buffer overflow

[Greg Kroah-Hartman]

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

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

From: Maciej Purski <m.purski@xxxxxxxxxxx>

[ Upstream commit 9378cecb1ce5d618b8aff4d65113ddcf72fc1011 ]

Buffer overflow error should not occur, as mode_fixup() callback
filters pixel clock value and it should never exceed 600000. However,
current implementation is not obviously safe and relies on
implementation of mode_fixup().

Make 'i' variable never reach unsafe value in order to avoid buffer
overflow error.

Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Fixes: bf1722ca ("drm/bridge/sii8620: rewrite hdmi start sequence")
Signed-off-by: Maciej Purski <m.purski@xxxxxxxxxxx>
Signed-off-by: Andrzej Hajda <a.hajda@xxxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/1511341718-6974-1-git-send-email-m.purski@xxxxxxxxxxx
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/bridge/sil-sii8620.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/gpu/drm/bridge/sil-sii8620.c
+++ b/drivers/gpu/drm/bridge/sil-sii8620.c
@@ -1228,7 +1228,7 @@ static void sii8620_start_video(struct s
 		int clk = ctx->pixel_clock * (ctx->use_packed_pixel ? 2 : 3);
 		int i;
 
-		for (i = 0; i < ARRAY_SIZE(clk_spec); ++i)
+		for (i = 0; i < ARRAY_SIZE(clk_spec) - 1; ++i)
 			if (clk < clk_spec[i].max_clk)
 				break;