Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider: - [High] Infinite probe deferral on platforms without PAS firmware support. - [High] TOCTOU race leading to NULL pointer dereference or UAF due to lockless `ops_ptr` access in the generic PAS wrappers. --
commit 58fde983bce7410af49e9cbf67e95a22f4ec47cb Author: Sumit Garg <[email protected]> drm/msm: Switch to generic PAS TZ APIs Switch drm/msm client drivers over to generic PAS TZ APIs. Generic PAS TZ service allows to support multiple TZ implementation backends like QTEE based SCM PAS service, OP-TEE based PAS service and any further future TZ backend service. > diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c > b/drivers/gpu/drm/msm/adreno/adreno_gpu.c > index c62c45bb0ddbb..c36382b23310a 100644 > --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c > +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c [ ... ] > @@ -146,10 +147,10 @@ static int zap_shader_load_mdt(struct msm_gpu *gpu, > const char *fwname, > goto out; > > /* Send the image to the secure world */ > - ret = qcom_scm_pas_auth_and_reset(pasid); > + ret = qcom_pas_auth_and_reset(pasid); [Severity: High] Does this new PAS API wrapper introduce a race condition? Looking at qcom_pas_auth_and_reset() in drivers/firmware/qcom/qcom_pas.c, it evaluates ops_ptr without try_module_get() or RCU protection: int qcom_pas_auth_and_reset(u32 pas_id) { if (!ops_ptr) return -ENODEV; return ops_ptr->auth_and_reset(ops_ptr->dev, pas_id); } If the backend module (like qcom-pas-tee) is unloaded concurrently, could ops_ptr become NULL after the check but before the dereference, leading to a NULL pointer dereference or use-after-free? [ ... ] > @@ -175,9 +176,9 @@ int adreno_zap_shader_load(struct msm_gpu *gpu, u32 pasid) > if (!zap_available) > return -ENODEV; > > - /* We need SCM to be able to load the firmware */ > - if (!qcom_scm_is_available()) { > - DRM_DEV_ERROR(&pdev->dev, "SCM is not available\n"); > + /* We need PAS to be able to load the firmware */ > + if (!qcom_pas_is_available()) { > + DRM_DEV_ERROR(&pdev->dev, "Qcom PAS is not available\n"); > return -EPROBE_DEFER; > } [Severity: High] Will this cause an infinite probe deferral on platforms without PAS firmware support? If a platform lacks both a zap shader node in the device tree and PAS firmware support, qcom_pas_is_available() will return false. This causes an immediate -EPROBE_DEFER before we can reach zap_shader_load_mdt(), which is where we would normally check the device tree and gracefully return -ENODEV. With the previous qcom_scm implementation, the SCM subsystem would probe and be available, allowing this check to pass so the code could proceed to the graceful fallback. -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=8
