Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
Pre-existing issues: - [Critical] The size calculation for the `msm_gem_submit` structure wraps around on 64-bit architectures, bypassing the `sz > SIZE_MAX` check and leading to a heap buffer overflow. - [High] Direct access to `ctx->vm` in `msm_ioctl_gem_submit` before the VM is guaranteed to be created causes a NULL pointer dereference. -- --- Patch [7]: [PATCH v6 07/16] drm/msm/a6xx: Access VM directly in submit path --- commit e716d49994df650aa89eca4941226567c71dbab5 Author: Rob Clark <[email protected]> drm/msm/a6xx: Access VM directly in submit path This patch changes the submit path to access the VM directly from the context rather than calling msm_context_vm() to lazily create it. It relies on the assumption that the ioctl has already ensured the VM is created prior to this point in the execution flow. > The GEM_SUBMIT ioctl has already ensured that the VM is created, so we > aren't expecting to lazily create the VM this deep into the ioctl. [Severity: High] This isn't a bug introduced by this patch, but does this assumption hold true? Looking at the ioctl entry point in msm_ioctl_gem_submit(), if userspace triggers this ioctl before any operation that creates the VM, the VM pointer is initially null: drivers/gpu/drm/msm/msm_gem_submit.c:msm_ioctl_gem_submit() { ... if (to_msm_vm(ctx->vm)->unusable) return UERR(EPIPE, dev, "context is unusable"); ... } Can this direct access to ctx->vm cause a null pointer dereference, since a preceding call to msm_context_vm() hasn't guaranteed its existence yet? > diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c > b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c > index e293b4ca808a4..9240c4af687c9 100644 > --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c > +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c > @@ -229,7 +229,7 @@ static void a6xx_set_pagetable(struct a6xx_gpu *a6xx_gpu, > { > bool sysprof = msm_gpu_sysprof_no_perfcntr_zap(&a6xx_gpu->base.base); > struct msm_context *ctx = submit->queue->ctx; > - struct drm_gpuvm *vm = msm_context_vm(submit->dev, ctx); > + struct drm_gpuvm *vm = ctx->vm; > struct adreno_gpu *adreno_gpu = &a6xx_gpu->base; > phys_addr_t ttbr; > u32 asid; While reviewing the submit path related to this change, I noticed another pre-existing issue in the submission creation logic: drivers/gpu/drm/msm/msm_gem_submit.c:submit_create() { ... sz = struct_size(submit, bos, nr_bos) + ((u64)nr_cmds * sizeof(submit->cmd[0])); if (sz > SIZE_MAX) return ERR_PTR(-ENOMEM); ... } [Severity: Critical] This is a pre-existing issue, but does this check protect against integer overflows effectively? Since sz is a 64-bit unsigned integer, the check sz > SIZE_MAX is mathematically impossible and acts as dead code. If a user provides a sufficiently large nr_bos, struct_size() saturates to SIZE_MAX. Adding a non-zero value for nr_cmds then causes sz to wrap around to a small value. Could this lead to an undersized buffer allocation from kzalloc() and a subsequent out-of-bounds heap write during initialization? -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=7
