On 15/10/2020 12:59, Chris Wilson wrote:
Matthew Auld noted that on more recent systems (such as the parser for
gen9) we may have objects that are larger than expected by the GEM uAPI
(i.e. greater than u32). These objects would have incorrect implicit
batch lengths, causing the parser to reject them for being incomplete,
or worse.

Based on a patch by Matthew Auld.

Reported-by: Matthew Auld <[email protected]>
Fixes: 435e8fc059db ("drm/i915: Allow parsing of unsized batches")
Testcase: igt/gem_exec_params/larger-than-life-batch
Signed-off-by: Chris Wilson <[email protected]>
Cc: Matthew Auld <[email protected]>
Cc: Mika Kuoppala <[email protected]>
Cc: Jon Bloomfield <[email protected]>
---
  drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c | 11 ++++++++---
  1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c 
b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index 4b09bcd70cf4..44b4558d5e86 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -287,8 +287,8 @@ struct i915_execbuffer {
        u64 invalid_flags; /** Set of execobj.flags that are invalid */
        u32 context_flags; /** Set of execobj.flags to insert from the ctx */
+ u64 batch_len; /** Length of batch within object */
        u32 batch_start_offset; /** Location within object of batch */
-       u32 batch_len; /** Length of batch within object */
        u32 batch_flags; /** Flags composed for emit_bb_start() */
        struct intel_gt_buffer_pool_node *batch_pool; /** pool node for batch 
buffer */
@@ -871,6 +871,10 @@ static int eb_lookup_vmas(struct i915_execbuffer *eb) if (eb->batch_len == 0)
                eb->batch_len = eb->batch->vma->size - eb->batch_start_offset;
+       if (eb->batch_len == 0) {
+               drm_dbg(&i915->drm, "Invalid batch length\n");
+               return -EINVAL;
+       }

This one should be impossible, or at least we should have hit the range_overflows check first?

Anyway, looks good to me,
Reviewed-by: Matthew Auld <[email protected]>
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