diff --git a/media/gpu/v4l2/v4l2_image_processor_backend.cc b/media/gpu/v4l2/v4l2_image_processor_backend.cc
index 4b79a8c90cb34..10f086044dc79 100644
--- a/media/gpu/v4l2/v4l2_image_processor_backend.cc
+++ b/media/gpu/v4l2/v4l2_image_processor_backend.cc
@@ -884,6 +884,15 @@ bool V4L2ImageProcessorBackend::EnqueueInputRecord(
             VideoFrame::PlaneSize(job_record->input_frame->format(), i,
                                   input_config_.size)
                 .GetArea();
+        // Clamp v4l2_plane.length to the actual span of this frame's plane.
+        // Without this, .length retains the QUERYBUF value sized from the
+        // *first* frame's stride, and a later smaller-mapping frame causes
+        // videobuf2 to pin/DMA-read past the renderer-supplied shmem.
+        const size_t plane_span =
+            base::checked_cast<size_t>(job_record->input_frame->stride(i)) *
+            VideoFrame::Rows(i, job_record->input_frame->format(),
+                             job_record->input_frame->coded_size().height());
+        buffer.SetPlaneSize(i, plane_span);
         buffer.SetPlaneBytesUsed(i, bytes_used);
         user_ptrs[i] = const_cast<uint8_t*>(job_record->input_frame->data(i));
       }