From b979f2d50a099f3402418d7ff5f26c3952fb08bb Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Sat, 17 Feb 2024 16:02:25 +0100 Subject: soc: qcom: pmic_glink_altmode: fix drm bridge use-after-free A recent DRM series purporting to simplify support for "transparent bridges" and handling of probe deferrals ironically exposed a use-after-free issue on pmic_glink_altmode probe deferral. This has manifested itself as the display subsystem occasionally failing to initialise and NULL-pointer dereferences during boot of machines like the Lenovo ThinkPad X13s. Specifically, the dp-hpd bridge is currently registered before all resources have been acquired which means that it can also be deregistered on probe deferrals. In the meantime there is a race window where the new aux bridge driver (or PHY driver previously) may have looked up the dp-hpd bridge and stored a (non-reference-counted) pointer to the bridge which is about to be deallocated. When the display controller is later initialised, this triggers a use-after-free when attaching the bridges: dp -> aux -> dp-hpd (freed) which may, for example, result in the freed bridge failing to attach: [drm:drm_bridge_attach [drm]] *ERROR* failed to attach bridge /soc@0/phy@88eb000 to encoder TMDS-31: -16 or a NULL-pointer dereference: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 ... Call trace: drm_bridge_attach+0x70/0x1a8 [drm] drm_aux_bridge_attach+0x24/0x38 [aux_bridge] drm_bridge_attach+0x80/0x1a8 [drm] dp_bridge_init+0xa8/0x15c [msm] msm_dp_modeset_init+0x28/0xc4 [msm] The DRM bridge implementation is clearly fragile and implicitly built on the assumption that bridges may never go away. In this case, the fix is to move the bridge registration in the pmic_glink_altmode driver to after all resources have been looked up. Incidentally, with the new dp-hpd bridge implementation, which registers child devices, this is also a requirement due to a long-standing issue in driver core that can otherwise lead to a probe deferral loop (see commit fbc35b45f9f6 ("Add documentation on meaning of -EPROBE_DEFER")). [DB: slightly fixed commit message by adding the word 'commit'] Fixes: 080b4e24852b ("soc: qcom: pmic_glink: Introduce altmode support") Fixes: 2bcca96abfbf ("soc: qcom: pmic-glink: switch to DRM_AUX_HPD_BRIDGE") Cc: # 6.3 Cc: Bjorn Andersson Cc: Dmitry Baryshkov Signed-off-by: Johan Hovold Reviewed-by: Bjorn Andersson Reviewed-by: Dmitry Baryshkov Signed-off-by: Dmitry Baryshkov Link: https://patchwork.freedesktop.org/patch/msgid/20240217150228.5788-4-johan+linaro@kernel.org --- drivers/soc/qcom/pmic_glink_altmode.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) (limited to 'drivers/soc') diff --git a/drivers/soc/qcom/pmic_glink_altmode.c b/drivers/soc/qcom/pmic_glink_altmode.c index 5fcd0fdd2faa..b3808fc24c69 100644 --- a/drivers/soc/qcom/pmic_glink_altmode.c +++ b/drivers/soc/qcom/pmic_glink_altmode.c @@ -76,7 +76,7 @@ struct pmic_glink_altmode_port { struct work_struct work; - struct device *bridge; + struct auxiliary_device *bridge; enum typec_orientation orientation; u16 svid; @@ -230,7 +230,7 @@ static void pmic_glink_altmode_worker(struct work_struct *work) else pmic_glink_altmode_enable_usb(altmode, alt_port); - drm_aux_hpd_bridge_notify(alt_port->bridge, + drm_aux_hpd_bridge_notify(&alt_port->bridge->dev, alt_port->hpd_state ? connector_status_connected : connector_status_disconnected); @@ -454,7 +454,7 @@ static int pmic_glink_altmode_probe(struct auxiliary_device *adev, alt_port->index = port; INIT_WORK(&alt_port->work, pmic_glink_altmode_worker); - alt_port->bridge = drm_dp_hpd_bridge_register(dev, to_of_node(fwnode)); + alt_port->bridge = devm_drm_dp_hpd_bridge_alloc(dev, to_of_node(fwnode)); if (IS_ERR(alt_port->bridge)) { fwnode_handle_put(fwnode); return PTR_ERR(alt_port->bridge); @@ -510,6 +510,16 @@ static int pmic_glink_altmode_probe(struct auxiliary_device *adev, } } + for (port = 0; port < ARRAY_SIZE(altmode->ports); port++) { + alt_port = &altmode->ports[port]; + if (!alt_port->bridge) + continue; + + ret = devm_drm_dp_hpd_bridge_add(dev, alt_port->bridge); + if (ret) + return ret; + } + altmode->client = devm_pmic_glink_register_client(dev, altmode->owner_id, pmic_glink_altmode_callback, -- cgit From f79ee78767ca60e7a2c89eacd2dbdf237d97e838 Mon Sep 17 00:00:00 2001 From: Rob Clark Date: Sat, 17 Feb 2024 16:02:26 +0100 Subject: soc: qcom: pmic_glink: Fix boot when QRTR=m We need to bail out before adding/removing devices if we are going to -EPROBE_DEFER. Otherwise boot can get stuck in a probe deferral loop due to a long-standing issue in driver core (see commit fbc35b45f9f6 ("Add documentation on meaning of -EPROBE_DEFER")). Deregistering the altmode child device can potentially also trigger bugs in the DRM bridge implementation, which does not expect bridges to go away. [DB: slightly fixed commit message by adding the word 'commit'] Suggested-by: Dmitry Baryshkov Signed-off-by: Rob Clark Link: https://lore.kernel.org/r/20231213210644.8702-1-robdclark@gmail.com [ johan: rebase on 6.8-rc4, amend commit message and mention DRM ] Fixes: 58ef4ece1e41 ("soc: qcom: pmic_glink: Introduce base PMIC GLINK driver") Cc: # 6.3 Cc: Bjorn Andersson Signed-off-by: Johan Hovold Reviewed-by: Bjorn Andersson Reviewed-by: Dmitry Baryshkov Reviewed-by: Neil Armstrong Signed-off-by: Dmitry Baryshkov Link: https://patchwork.freedesktop.org/patch/msgid/20240217150228.5788-5-johan+linaro@kernel.org --- drivers/soc/qcom/pmic_glink.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) (limited to 'drivers/soc') diff --git a/drivers/soc/qcom/pmic_glink.c b/drivers/soc/qcom/pmic_glink.c index f4bfd24386f1..f913e9bd57ed 100644 --- a/drivers/soc/qcom/pmic_glink.c +++ b/drivers/soc/qcom/pmic_glink.c @@ -265,10 +265,17 @@ static int pmic_glink_probe(struct platform_device *pdev) pg->client_mask = *match_data; + pg->pdr = pdr_handle_alloc(pmic_glink_pdr_callback, pg); + if (IS_ERR(pg->pdr)) { + ret = dev_err_probe(&pdev->dev, PTR_ERR(pg->pdr), + "failed to initialize pdr\n"); + return ret; + } + if (pg->client_mask & BIT(PMIC_GLINK_CLIENT_UCSI)) { ret = pmic_glink_add_aux_device(pg, &pg->ucsi_aux, "ucsi"); if (ret) - return ret; + goto out_release_pdr_handle; } if (pg->client_mask & BIT(PMIC_GLINK_CLIENT_ALTMODE)) { ret = pmic_glink_add_aux_device(pg, &pg->altmode_aux, "altmode"); @@ -281,17 +288,11 @@ static int pmic_glink_probe(struct platform_device *pdev) goto out_release_altmode_aux; } - pg->pdr = pdr_handle_alloc(pmic_glink_pdr_callback, pg); - if (IS_ERR(pg->pdr)) { - ret = dev_err_probe(&pdev->dev, PTR_ERR(pg->pdr), "failed to initialize pdr\n"); - goto out_release_aux_devices; - } - service = pdr_add_lookup(pg->pdr, "tms/servreg", "msm/adsp/charger_pd"); if (IS_ERR(service)) { ret = dev_err_probe(&pdev->dev, PTR_ERR(service), "failed adding pdr lookup for charger_pd\n"); - goto out_release_pdr_handle; + goto out_release_aux_devices; } mutex_lock(&__pmic_glink_lock); @@ -300,8 +301,6 @@ static int pmic_glink_probe(struct platform_device *pdev) return 0; -out_release_pdr_handle: - pdr_handle_release(pg->pdr); out_release_aux_devices: if (pg->client_mask & BIT(PMIC_GLINK_CLIENT_BATT)) pmic_glink_del_aux_device(pg, &pg->ps_aux); @@ -311,6 +310,8 @@ out_release_altmode_aux: out_release_ucsi_aux: if (pg->client_mask & BIT(PMIC_GLINK_CLIENT_UCSI)) pmic_glink_del_aux_device(pg, &pg->ucsi_aux); +out_release_pdr_handle: + pdr_handle_release(pg->pdr); return ret; } -- cgit