Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider: - [High] Double unregister of platform device in error paths causes Use-After-Free - [Medium] Incorrect pointer passed to devm_add_action_or_reset causes resource leak of audio platform device --
commit 2bc8391d481088826fa13d96d05225e5c15e6457 Author: AngeloGioacchino Del Regno <[email protected]> drm/mediatek: mtk_dp: Fix hdmi codec and phy driver unregistration This commit introduces devm actions to unregister the HDMI Codec and DisplayPort PHY platform devices, preventing multiple instantiations during probe deferrals. > diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c > b/drivers/gpu/drm/mediatek/mtk_dp.c > index eefbc7e0f9c8d..2c738c16dafab 100644 > --- a/drivers/gpu/drm/mediatek/mtk_dp.c > +++ b/drivers/gpu/drm/mediatek/mtk_dp.c [ ... ] > @@ -2680,18 +2687,29 @@ static int mtk_dp_register_audio_driver(struct device > *dev) > .data = mtk_dp, > .no_capture_mute = 1, > }; > + int ret; > > mtk_dp->audio_pdev = platform_device_register_data(dev, > HDMI_CODEC_DRV_NAME, > PLATFORM_DEVID_AUTO, > &codec_data, > sizeof(codec_data)); > - return PTR_ERR_OR_ZERO(mtk_dp->audio_pdev); > + if (IS_ERR(mtk_dp->audio_pdev)) > + return PTR_ERR(mtk_dp->audio_pdev); > + > + ret = devm_add_action_or_reset(dev, mtk_dp_unregister_pdevs, > mtk_dp->phy_dev); [Severity: Medium] Is the correct platform device pointer being passed here? This registers a cleanup action using mtk_dp->phy_dev rather than the newly created mtk_dp->audio_pdev. This will likely leak the audio device on probe deferral or driver unbind, and may attempt to unregister the PHY device at the wrong time instead. > + if (ret) { > + platform_device_unregister(mtk_dp->audio_pdev); > + return dev_err_probe(dev, ret, > + "Failed to add codec unregister devm > action"); > + } > + return 0; > } > > static int mtk_dp_register_phy(struct mtk_dp *mtk_dp) > { > struct device *dev = mtk_dp->dev; > + int ret; > > mtk_dp->phy_dev = platform_device_register_data(dev, "mediatek-dp-phy", > PLATFORM_DEVID_AUTO, > @@ -2701,6 +2719,13 @@ static int mtk_dp_register_phy(struct mtk_dp *mtk_dp) > return dev_err_probe(dev, PTR_ERR(mtk_dp->phy_dev), > "Failed to create device > mediatek-dp-phy\n"); > > + ret = devm_add_action_or_reset(dev, mtk_dp_unregister_pdevs, > mtk_dp->phy_dev); > + if (ret) { > + platform_device_unregister(mtk_dp->phy_dev); [Severity: High] Could this cause a use-after-free? When devm_add_action_or_reset() fails, it automatically executes the cleanup action, which calls platform_device_unregister() on mtk_dp->phy_dev. Calling platform_device_unregister() a second time here would double-free the device. > + return dev_err_probe(dev, ret, > + "Failed to add phy unregister devm > action"); > + } > + > mtk_dp_get_calibration_data(mtk_dp); > > mtk_dp->phy = devm_phy_get(&mtk_dp->phy_dev->dev, "dp"); [Severity: High] Can the error path for devm_phy_get() also trigger a double-free? Looking at the rest of mtk_dp_register_phy() just below this diff: mtk_dp_register_phy() { ... mtk_dp->phy = devm_phy_get(&mtk_dp->phy_dev->dev, "dp"); if (IS_ERR(mtk_dp->phy)) { platform_device_unregister(mtk_dp->phy_dev); return dev_err_probe(dev, PTR_ERR(mtk_dp->phy), "Failed to get phy\n"); } ... } Since the devm unregister action was successfully registered above, returning an error here will trigger the devm unwind loop. That will unregister the device a second time after this explicit platform_device_unregister() call. -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=3
