Hi Laurent,
Thanks for the feedback.
> -----Original Message-----
> From: dri-devel <dri-devel-bounces@xxxxxxxxxxxxxxxxxxxxx> On Behalf Of Laurent Pinchart
> Sent: 16 November 2024 15:32
> Subject: Re: [PATCH v4 1/3] drm: adv7511: Fix use-after-free in adv7533_attach_dsi()
>
> 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.
Oops. Missed it.
>
> > @@ -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().
OK got it, Then will keep the of_node in the adv7511 structure to make the error label and
error handling code in sync.
Cheers,
Biju
>
> > 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
