linux-kernel - [PATCH 5.15 121/530] media: cedrus: Fix endless loop in cedrus_h265_skip

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Message-Id: <20221024113050.527524218@linuxfoundation.org>
Date:   Mon, 24 Oct 2022 13:27:45 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Nicolas Dufresne <nicolas.dufresne@...labora.com>,
        Dmitry Osipenko <dmitry.osipenko@...labora.com>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Mauro Carvalho Chehab <mchehab@...nel.org>
Subject: [PATCH 5.15 121/530] media: cedrus: Fix endless loop in cedrus_h265_skip_bits()

From: Dmitry Osipenko <dmitry.osipenko@...labora.com>

commit 91db7a3fc7fe670cf1770a398a43bb4a1f776bf1 upstream.

The busy status bit may never de-assert if number of programmed skip
bits is incorrect, resulting in a kernel hang because the bit is polled
endlessly in the code. Fix it by adding timeout for the bit-polling.
This problem is reproducible by setting the data_bit_offset field of
the HEVC slice params to a wrong value by userspace.

Cc: stable@...r.kernel.org
Fixes: 7678c5462680 (media: cedrus: Fix decoding for some HEVC videos)
Reported-by: Nicolas Dufresne <nicolas.dufresne@...labora.com>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@...labora.com>
Signed-off-by: Nicolas Dufresne <nicolas.dufresne@...labora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@...all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/staging/media/sunxi/cedrus/cedrus_h265.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
+++ b/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
@@ -234,8 +234,9 @@ static void cedrus_h265_skip_bits(struct
 		cedrus_write(dev, VE_DEC_H265_TRIGGER,
 			     VE_DEC_H265_TRIGGER_FLUSH_BITS |
 			     VE_DEC_H265_TRIGGER_TYPE_N_BITS(tmp));
-		while (cedrus_read(dev, VE_DEC_H265_STATUS) & VE_DEC_H265_STATUS_VLD_BUSY)
-			udelay(1);
+
+		if (cedrus_wait_for(dev, VE_DEC_H265_STATUS, VE_DEC_H265_STATUS_VLD_BUSY))
+			dev_err_ratelimited(dev->dev, "timed out waiting to skip bits\n");
 
 		count += tmp;
 	}