Hi Biju,
Thank you for the patch.
On Sat, Nov 16, 2024 at 12:54:10PM +0000, Biju Das wrote:
> The host_node pointer was assigned and freed in adv7533_parse_dt(), and
> later, adv7533_attach_dsi() used the same. Fix this use-after-free issue
> with the below changes:
>
> 1. Drop host_node from struct adv7511 and instead use a local pointer in
> adv7511_probe().
> 2. Update adv7533_parse_dt() to return the host_node.
> 3. Pass the host_node as a parameter to adv7533_attach_dsi().
> 4. Call of_node_put() after use.
>
> Fixes: 1e4d58cd7f88 ("drm/bridge: adv7533: Create a MIPI DSI device")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> ---
> Changes in v4:
> - Updated commit description.
> - Dropped host_node from struct adv7511 and instead used a local pointer
> in probe(). Also freeing of host_node pointer after use is done in
> probe().
> Changes in v3:
> - Replace __free construct with readable of_node_put().
> Changes in v2:
> - Added the tag "Cc: stable@xxxxxxxxxxxxxxx" in the sign-off area.
> - Dropped Archit Taneja invalid Mail address
> ---
> drivers/gpu/drm/bridge/adv7511/adv7511.h | 6 +++---
> drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 22 ++++++++++++++------
> drivers/gpu/drm/bridge/adv7511/adv7533.c | 20 +++++++++---------
> 3 files changed, 29 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511.h b/drivers/gpu/drm/bridge/adv7511/adv7511.h
> index ec0b7f3d889c..9f3fae7cc597 100644
> --- a/drivers/gpu/drm/bridge/adv7511/adv7511.h
> +++ b/drivers/gpu/drm/bridge/adv7511/adv7511.h
> @@ -383,7 +383,6 @@ struct adv7511 {
> struct regulator_bulk_data *supplies;
>
> /* ADV7533 DSI RX related params */
> - struct device_node *host_node;
> struct mipi_dsi_device *dsi;
> u8 num_dsi_lanes;
> bool use_timing_gen;
> @@ -417,8 +416,9 @@ enum drm_mode_status adv7533_mode_valid(struct adv7511 *adv,
> const struct drm_display_mode *mode);
> int adv7533_patch_registers(struct adv7511 *adv);
> int adv7533_patch_cec_registers(struct adv7511 *adv);
> -int adv7533_attach_dsi(struct adv7511 *adv);
> -int adv7533_parse_dt(struct device_node *np, struct adv7511 *adv);
> +int adv7533_attach_dsi(struct adv7511 *adv, struct device_node *host_node);
> +struct device_node *adv7533_parse_dt(struct device_node *np,
> + struct adv7511 *adv);
>
> #ifdef CONFIG_DRM_I2C_ADV7511_AUDIO
> int adv7511_audio_init(struct device *dev, struct adv7511 *adv7511);
> diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> index eb5919b38263..3f1f309791a5 100644
> --- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> +++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> @@ -1209,6 +1209,7 @@ static int adv7511_parse_dt(struct device_node *np,
> static int adv7511_probe(struct i2c_client *i2c)
> {
> struct adv7511_link_config link_config;
> + struct device_node *host_node = NULL;
> struct adv7511 *adv7511;
> struct device *dev = &i2c->dev;
> unsigned int val;
> @@ -1233,12 +1234,17 @@ static int adv7511_probe(struct i2c_client *i2c)
> if (ret && ret != -ENODEV)
> return ret;
>
> - if (adv7511->info->link_config)
> + if (adv7511->info->link_config) {
> ret = adv7511_parse_dt(dev->of_node, &link_config);
> - else
> - ret = adv7533_parse_dt(dev->of_node, adv7511);
> - if (ret)
> - return ret;
> + if (ret)
> + return ret;
> + }
> +
> + if (adv7511->info->has_dsi) {
> + host_node = adv7533_parse_dt(dev->of_node, adv7511);
> + if (IS_ERR(host_node))
> + return PTR_ERR(host_node);
> + }
>
> ret = adv7511_init_regulators(adv7511);
> if (ret)
host_node is leaked here.
> @@ -1343,9 +1349,11 @@ static int adv7511_probe(struct i2c_client *i2c)
> }
>
> if (adv7511->info->has_dsi) {
> - ret = adv7533_attach_dsi(adv7511);
> + ret = adv7533_attach_dsi(adv7511, host_node);
> if (ret)
> goto err_unregister_audio;
> +
> + of_node_put(host_node);
> }
>
> return 0;
> @@ -1362,6 +1370,8 @@ static int adv7511_probe(struct i2c_client *i2c)
> err_i2c_unregister_edid:
> i2c_unregister_device(adv7511->i2c_edid);
> uninit_regulators:
> + if (host_node)
> + of_node_put(host_node);
The error label and the error handling code are now out of sync, making
the code harder to read and more error-prone.
Error handling is why I proposed keeping of_node in the adv7511
structure, and calling of_node_put() in adv7511_remove() and at the end
of the error handling path in adv7511_probe().
> adv7511_uninit_regulators(adv7511);
>
> return ret;
> diff --git a/drivers/gpu/drm/bridge/adv7511/adv7533.c b/drivers/gpu/drm/bridge/adv7511/adv7533.c
> index 4481489aaf5e..5d0e55ef4028 100644
> --- a/drivers/gpu/drm/bridge/adv7511/adv7533.c
> +++ b/drivers/gpu/drm/bridge/adv7511/adv7533.c
> @@ -131,7 +131,7 @@ int adv7533_patch_cec_registers(struct adv7511 *adv)
> ARRAY_SIZE(adv7533_cec_fixed_registers));
> }
>
> -int adv7533_attach_dsi(struct adv7511 *adv)
> +int adv7533_attach_dsi(struct adv7511 *adv, struct device_node *host_node)
> {
> struct device *dev = &adv->i2c_main->dev;
> struct mipi_dsi_host *host;
> @@ -142,7 +142,7 @@ int adv7533_attach_dsi(struct adv7511 *adv)
> .node = NULL,
> };
>
> - host = of_find_mipi_dsi_host_by_node(adv->host_node);
> + host = of_find_mipi_dsi_host_by_node(host_node);
> if (!host)
> return dev_err_probe(dev, -EPROBE_DEFER,
> "failed to find dsi host\n");
> @@ -166,22 +166,22 @@ int adv7533_attach_dsi(struct adv7511 *adv)
> return 0;
> }
>
> -int adv7533_parse_dt(struct device_node *np, struct adv7511 *adv)
> +struct device_node *adv7533_parse_dt(struct device_node *np,
> + struct adv7511 *adv)
> {
> + struct device_node *host_node;
> u32 num_lanes;
>
> of_property_read_u32(np, "adi,dsi-lanes", &num_lanes);
>
> if (num_lanes < 1 || num_lanes > 4)
> - return -EINVAL;
> + return ERR_PTR(-EINVAL);
>
> adv->num_dsi_lanes = num_lanes;
>
> - adv->host_node = of_graph_get_remote_node(np, 0, 0);
> - if (!adv->host_node)
> - return -ENODEV;
> -
> - of_node_put(adv->host_node);
> + host_node = of_graph_get_remote_node(np, 0, 0);
> + if (!host_node)
> + return ERR_PTR(-ENODEV);
>
> adv->use_timing_gen = !of_property_read_bool(np,
> "adi,disable-timing-generator");
> @@ -190,5 +190,5 @@ int adv7533_parse_dt(struct device_node *np, struct adv7511 *adv)
> adv->rgb = true;
> adv->embedded_sync = false;
>
> - return 0;
> + return host_node;
> }
--
Regards,
Laurent Pinchart
