rusticl/kernel: rework validation in clSetKernelExecInfo

We should use the cl_slice code to get proper validation, which also makes
it simpler to read out data and gets rid of some UB there.

This also fixes CL_KERNEL_EXEC_INFO_SVM_PTRS with param_value being null.

Cc: mesa-stable
Reviewed-by: Adam Jackson <ajax@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32942>
(cherry picked from commit 35a9829391)

.pick_status.json

@@ -2434,7 +2434,7 @@
         "description": "rusticl/kernel: rework validation in clSetKernelExecInfo",
         "nominated": true,
         "nomination_type": 1,
-        "resolution": 0,
+        "resolution": 1,
         "main_sha": null,
         "because_sha": null,
         "notes": null

src/gallium/frontends/rusticl/api/kernel.rs

@@ -501,22 +501,29 @@ fn set_kernel_exec_info(
         return Err(CL_INVALID_OPERATION);
     }
 
-    // CL_INVALID_VALUE ... if param_value is NULL
-    if param_value.is_null() {
-        return Err(CL_INVALID_VALUE);
-    }
-
     // CL_INVALID_VALUE ... if the size specified by param_value_size is not valid.
     match param_name {
         CL_KERNEL_EXEC_INFO_SVM_PTRS | CL_KERNEL_EXEC_INFO_SVM_PTRS_ARM => {
-            // it's a list of pointers
-            if param_value_size % mem::size_of::<*const c_void>() != 0 {
-                return Err(CL_INVALID_VALUE);
+            // To specify that no SVM allocations will be accessed by a kernel other than those set
+            // as kernel arguments, specify an empty set by passing param_value_size equal to zero
+            // and param_value equal to NULL.
+            if !param_value.is_null() || param_value_size != 0 {
+                let _ = unsafe {
+                    cl_slice::from_raw_parts_bytes_len::<*const c_void>(
+                        param_value,
+                        param_value_size,
+                    )?
+                };
             }
         }
         CL_KERNEL_EXEC_INFO_SVM_FINE_GRAIN_SYSTEM
         | CL_KERNEL_EXEC_INFO_SVM_FINE_GRAIN_SYSTEM_ARM => {
-            if param_value_size != mem::size_of::<cl_bool>() {
+            let val = unsafe {
+                cl_slice::from_raw_parts_bytes_len::<cl_bool>(param_value, param_value_size)?
+            };
+
+            // we must explicitly check that we only got one element
+            if val.len() != 1 {
                 return Err(CL_INVALID_VALUE);
             }
         }

src/gallium/frontends/rusticl/api/util.rs

@@ -560,6 +560,7 @@ pub mod cl_slice {
     use crate::api::util::CLResult;
     use mesa_rust_util::ptr::addr;
     use rusticl_opencl_gen::CL_INVALID_VALUE;
+    use std::ffi::c_void;
     use std::mem;
     use std::slice;
 
@@ -586,6 +587,22 @@ pub mod cl_slice {
         unsafe { Ok(slice::from_raw_parts(data, len)) }
     }
 
+    /// same as [self::from_raw_parts] just that `len` is provided in bytes and must be a multiple
+    /// of Ts size.
+    #[inline]
+    pub unsafe fn from_raw_parts_bytes_len<'a, T>(
+        data: *const c_void,
+        len: usize,
+    ) -> CLResult<&'a [T]> {
+        let size = mem::size_of::<T>();
+        if len % size != 0 {
+            return Err(CL_INVALID_VALUE);
+        }
+
+        let len = len / size;
+        unsafe { self::from_raw_parts(data.cast(), len) }
+    }
+
     /// Wrapper around [`std::slice::from_raw_parts_mut`] that returns `Err(CL_INVALID_VALUE)` if any of these conditions is met:
     /// - `data` is null
     /// - `data` is not correctly aligned for `T`