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drm/omap: Fix possible NULL dereference

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smatch reports:

drivers/gpu/drm/omapdrm/dss/base.c:176 omapdss_device_disconnect() error: we previously assumed 'src' could be null (see line 169)

This code is mostly from a time when omapdrm had its own display device
model. I can't honestly remember the details, and I don't think it's
worth digging in deeply into that for a legacy driver.

However, it looks like we only call omapdss_device_disconnect() and
omapdss_device_connect() with NULL as the src parameter. We can thus
drop the src parameter from both functions, and fix the smatch warning.

I don't think omapdss_device_disconnect() ever gets NULL for the dst
parameter (if it did, we'd crash soon after returning from the
function), but I have kept the !dst check, just in case, but I added a
WARN_ON() there.

Also, if the dst parameter can be NULL, we can't always get the struct
dss_device pointer from dst->dss (which is only used for a debug print).
To make sure we can't hit that issue, do it similarly to the
omapdss_device_connect() function: add 'struct dss_device *dss' as the
first parameter, so that we always have it regardless of the dst.

Fixes: 79107f274b ("drm/omap: Add support for drm_bridge")
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240806-omapdrm-misc-fixes-v1-1-15d31aea0831@ideasonboard.com
This commit is contained in:
Tomi Valkeinen 2024-08-06 16:50:27 +03:00
parent ef77507bc8
commit a88fee2d67
3 changed files with 9 additions and 23 deletions
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25
drivers/gpu/drm/omapdrm/dss/base.c
View File

@ -139,21 +139,13 @@ static bool omapdss_device_is_connected(struct omap_dss_device *dssdev)
}
int omapdss_device_connect(struct dss_device *dss,
struct omap_dss_device *src,
struct omap_dss_device *dst)
{
dev_dbg(&dss->pdev->dev, "connect(%s, %s)\n",
src ? dev_name(src->dev) : "NULL",
dev_dbg(&dss->pdev->dev, "connect(%s)\n",
dst ? dev_name(dst->dev) : "NULL");
if (!dst) {
/*
* The destination is NULL when the source is connected to a
* bridge instead of a DSS device. Stop here, we will attach
* the bridge later when we will have a DRM encoder.
*/
return src && src->bridge ? 0 : -EINVAL;
}
if (!dst)
return -EINVAL;
if (omapdss_device_is_connected(dst))
return -EBUSY;
@ -163,19 +155,14 @@ int omapdss_device_connect(struct dss_device *dss,
return 0;
}
void omapdss_device_disconnect(struct omap_dss_device *src,
void omapdss_device_disconnect(struct dss_device *dss,
struct omap_dss_device *dst)
{
struct dss_device *dss = src ? src->dss : dst->dss;
dev_dbg(&dss->pdev->dev, "disconnect(%s, %s)\n",
src ? dev_name(src->dev) : "NULL",
dev_dbg(&dss->pdev->dev, "disconnect(%s)\n",
dst ? dev_name(dst->dev) : "NULL");
if (!dst) {
WARN_ON(!src->bridge);
if (WARN_ON(!dst))
return;
}
if (!dst->id && !omapdss_device_is_connected(dst)) {
WARN_ON(1);

3
drivers/gpu/drm/omapdrm/dss/omapdss.h
View File

@ -242,9 +242,8 @@ struct omap_dss_device *omapdss_device_get(struct omap_dss_device *dssdev);
void omapdss_device_put(struct omap_dss_device *dssdev);
struct omap_dss_device *omapdss_find_device_by_node(struct device_node *node);
int omapdss_device_connect(struct dss_device *dss,
struct omap_dss_device *src,
struct omap_dss_device *dst);
void omapdss_device_disconnect(struct omap_dss_device *src,
void omapdss_device_disconnect(struct dss_device *dss,
struct omap_dss_device *dst);
int omap_dss_get_num_overlay_managers(void);

4
drivers/gpu/drm/omapdrm/omap_drv.c
View File

@ -307,7 +307,7 @@ static void omap_disconnect_pipelines(struct drm_device *ddev)
for (i = 0; i < priv->num_pipes; i++) {
struct omap_drm_pipeline *pipe = &priv->pipes[i];
omapdss_device_disconnect(NULL, pipe->output);
omapdss_device_disconnect(priv->dss, pipe->output);
omapdss_device_put(pipe->output);
pipe->output = NULL;
@ -325,7 +325,7 @@ static int omap_connect_pipelines(struct drm_device *ddev)
int r;
for_each_dss_output(output) {
r = omapdss_device_connect(priv->dss, NULL, output);
r = omapdss_device_connect(priv->dss, output);
if (r == -EPROBE_DEFER) {
omapdss_device_put(output);
return r;