mesa/main: Fix overflow in validation of DispatchComputeGroupSizeARB

An uint64_t can store the result of multiplying two GLuint (uint32_t),
so use that property to check for overflow when calculating the total.

Change the error message so we don't need to care about the actual
total -- which means we don't need a larger than 64-bit value to hold
it.

Fixes: 45ab63c0cb2 ("mesa/main: add support for ARB_compute_variable_groups_size")
Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Tested-by: Marge Bot <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4240>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4240>

diff --git a/src/mesa/main/compute.c b/src/mesa/main/compute.c
index 84ae7562c304d07e4c2560c542b838e5d4ed9a0b..794b5d035bf8ee71448c83b6a488a6e39a400f50 100644 (file)
--- a/src/mesa/main/compute.c
+++ b/src/mesa/main/compute.c
@@ -103,8 +103,6 @@ validate_DispatchComputeGroupSizeARB(struct gl_context *ctx,
                                      const GLuint *num_groups,
                                      const GLuint *group_size)
 {
-   GLuint total_invocations = 1;
-
    if (!check_valid_to_compute(ctx, "glDispatchComputeGroupSizeARB"))
       return GL_FALSE;
 
@@ -153,8 +151,6 @@ validate_DispatchComputeGroupSizeARB(struct gl_context *ctx,
                      "glDispatchComputeGroupSizeARB(group_size_%c)", 'x' + i);
          return GL_FALSE;
       }
-
-      total_invocations *= group_size[i];
    }
 
    /* The ARB_compute_variable_group_size spec says:
@@ -165,11 +161,19 @@ validate_DispatchComputeGroupSizeARB(struct gl_context *ctx,
     *  for compute shaders with variable group size
     *  (MAX_COMPUTE_VARIABLE_GROUP_INVOCATIONS_ARB)."
     */
+   uint64_t total_invocations = group_size[0] * group_size[1];
+   if (total_invocations <= UINT32_MAX) {
+      /* Only bother multiplying the third value if total still fits in
+       * 32-bit, since MaxComputeVariableGroupInvocations is also 32-bit.
+       */
+      total_invocations *= group_size[2];
+   }
    if (total_invocations > ctx->Const.MaxComputeVariableGroupInvocations) {
       _mesa_error(ctx, GL_INVALID_VALUE,
                   "glDispatchComputeGroupSizeARB(product of local_sizes "
                   "exceeds MAX_COMPUTE_VARIABLE_GROUP_INVOCATIONS_ARB "
-                  "(%d > %d))", total_invocations,
+                  "(%u * %u * %u > %u))",
+                  group_size[0], group_size[1], group_size[2],
                   ctx->Const.MaxComputeVariableGroupInvocations);
       return GL_FALSE;
    }