linux-kernel - [PATCH v2 1/2] staging: media: tegra-video: fix chan->mipi value on error

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Date:   Wed,  2 Nov 2022 12:01:01 +0100
From:   luca.ceresoli@...tlin.com
To:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Sowjanya Komatineni <skomatineni@...dia.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Dmitry Osipenko <digetx@...il.com>
Cc:     Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        linux-media@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org,
        Luca Ceresoli <luca.ceresoli@...tlin.com>,
        stable@...r.kernel.org, Dan Carpenter <dan.carpenter@...cle.com>
Subject: [PATCH v2 1/2] staging: media: tegra-video: fix chan->mipi value on error

From: Luca Ceresoli <luca.ceresoli@...tlin.com>

chan->mipi takes the return value of tegra_mipi_request() which can be a
valid pointer or an error. However chan->mipi is checked in several places,
including error-cleanup code in tegra_csi_channels_cleanup(), as 'if
(chan->mipi)', which suggests the initial intent was that chan->mipi should
be either NULL or a valid pointer, never an error. As a consequence,
cleanup code in case of tegra_mipi_request() errors would dereference an
invalid pointer.

Fix by ensuring chan->mipi always contains either NULL or a void pointer.

Also add that to the documentation.

Fixes: 523c857e34ce ("media: tegra-video: Add CSI MIPI pads calibration")
Cc: stable@...r.kernel.org
Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Luca Ceresoli <luca.ceresoli@...tlin.com>

---

This patch was added in v2.
---
 drivers/staging/media/tegra-video/csi.c | 1 +
 drivers/staging/media/tegra-video/csi.h | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/media/tegra-video/csi.c b/drivers/staging/media/tegra-video/csi.c
index b26e44adb2be..6b59ef55c525 100644
--- a/drivers/staging/media/tegra-video/csi.c
+++ b/drivers/staging/media/tegra-video/csi.c
@@ -448,6 +448,7 @@ static int tegra_csi_channel_alloc(struct tegra_csi *csi,
 	chan->mipi = tegra_mipi_request(csi->dev, node);
 	if (IS_ERR(chan->mipi)) {
 		ret = PTR_ERR(chan->mipi);
+		chan->mipi = NULL;
 		dev_err(csi->dev, "failed to get mipi device: %d\n", ret);
 	}
 
diff --git a/drivers/staging/media/tegra-video/csi.h b/drivers/staging/media/tegra-video/csi.h
index 4ee05a1785cf..6960ea2e3d36 100644
--- a/drivers/staging/media/tegra-video/csi.h
+++ b/drivers/staging/media/tegra-video/csi.h
@@ -56,7 +56,7 @@ struct tegra_csi;
  * @framerate: active framerate for TPG
  * @h_blank: horizontal blanking for TPG active format
  * @v_blank: vertical blanking for TPG active format
- * @mipi: mipi device for corresponding csi channel pads
+ * @mipi: mipi device for corresponding csi channel pads, or NULL if not applicable (TPG, error)
  * @pixel_rate: active pixel rate from the sensor on this channel
  */
 struct tegra_csi_channel {
-- 
2.34.1