Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
New issues: - [Medium] The check `!vm` fails to detect shared VMs, breaking the `MSM_BO_NO_SHARE` contract. Pre-existing issues: - [Critical] NULL Pointer Dereference when accessing uninitialized `ctx->vm` in `msm_ioctl_gem_submit`. -- --- Patch [12]: [PATCH v6 12/16] drm/msm/gem: Validate lazy VM in GEM_NEW --- commit 2c5a1210206f5856b0becc6857b23e80e4e3fe79 Author: Rob Clark <[email protected]> drm/msm/gem: Validate lazy VM in GEM_NEW This commit adds a check in msm_gem_new_handle() to ensure the VM is available before creating a BO with MSM_BO_NO_SHARE. It prevents a NULL pointer dereference that could occur if a BO is created before any BOs have been mapped. > diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c > index 12d9b8a9c360a..b9da5b7ce8a31 100644 > --- a/drivers/gpu/drm/msm/msm_gem.c > +++ b/drivers/gpu/drm/msm/msm_gem.c > @@ -1139,9 +1139,13 @@ int msm_gem_new_handle(struct drm_device *dev, struct > drm_file *file, > int ret; > > if (flags & MSM_BO_NO_SHARE) { > + struct msm_drm_private *priv = dev->dev_private; > struct msm_context *ctx = file->driver_priv; > struct drm_gpuvm *vm = msm_context_vm(dev, ctx); > > + if (!priv->gpu || !vm) > + return UERR(EINVAL, dev, "not supported with shared > VM"); > + [Severity: Medium] Does the check for !vm correctly detect if a shared VM is in use? If a platform does not support private VMs and falls back to the global VM, msm_context_vm() will return the shared gpu->vm. In this case, !vm will evaluate to false, allowing the allocation to proceed. Could this allow the MSM_BO_NO_SHARE flag to succeed while silently sharing the global reservation object, defeating the purpose of the flag and creating hidden lock contention? Would it be better to check if vm == priv->gpu->vm to ensure a private VM is actually in use? > r_obj = drm_gpuvm_resv_obj(vm); > } > [Severity: Critical] This is a pre-existing issue, but does msm_ioctl_gem_submit() have a similar problem with lazy VM initialization? Looking at msm_ioctl_gem_submit() in drivers/gpu/drm/msm/msm_gem_submit.c: if (!gpu) return -ENXIO; if (args->pad) return -EINVAL; if (to_msm_vm(ctx->vm)->unusable) return UERR(EPIPE, dev, "context is unusable"); If a userspace process calls the DRM_IOCTL_MSM_GEM_SUBMIT ioctl immediately after opening the DRM device, ctx->vm will be NULL because no previous operation has initialized it. Since this code accesses ctx->vm directly instead of using msm_context_vm(), will this cause a NULL pointer dereference when to_msm_vm() evaluates to NULL and ->unusable is accessed? -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=12
