On 03/05/2021 16:57, Jason Ekstrand wrote:
There's no sense in allowing userspace to create more engines than it
can possibly access via execbuf.
Signed-off-by: Jason Ekstrand <jason@xxxxxxxxxxxxxx>
Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
FWIW, again for the record, my advice is not to land this one. It makes
no sense and it is actively disruptive for no benefit.
Regards,
Tvrtko
---
drivers/gpu/drm/i915/gem/i915_gem_context.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index be42dc918ef6f..8e254d83d65f2 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -1640,11 +1640,11 @@ set_engines(struct i915_gem_context *ctx,
return -EINVAL;
}
- /*
- * Note that I915_EXEC_RING_MASK limits execbuf to only using the
- * first 64 engines defined here.
- */
num_engines = (args->size - sizeof(*user)) / sizeof(*user->engines);
+ /* RING_MASK has no shift so we can use it directly here */
+ if (num_engines > I915_EXEC_RING_MASK + 1)
+ return -EINVAL;
+
set.engines = alloc_engines(num_engines);
if (!set.engines)
return -ENOMEM;
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