shithub: libvpx

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Prevent reading of uninitialized value

This commit added a check of reference frame to make sure that pre
buffer pointers are initialized only when necessary and make them
to 0 if ref frame is intra, hence those buffer should never be used.

Change-Id: Ieb474fcd9feb759f02e2f9c282b7348a8fa31117

--- a/vp8/decoder/decodeframe.c

+++ b/vp8/decoder/decodeframe.c

@@ -631,9 +631,17 @@

             xd->dst.u_buffer = dst_buffer[1] + recon_uvoffset;

             xd->dst.v_buffer = dst_buffer[2] + recon_uvoffset;

-            xd->pre.y_buffer = ref_buffer[xd->mode_info_context->mbmi.ref_frame][0] + recon_yoffset;

-            xd->pre.u_buffer = ref_buffer[xd->mode_info_context->mbmi.ref_frame][1] + recon_uvoffset;

-            xd->pre.v_buffer = ref_buffer[xd->mode_info_context->mbmi.ref_frame][2] + recon_uvoffset;

+            if (xd->mode_info_context->mbmi.ref_frame >= LAST_FRAME) {

+              MV_REFERENCE_FRAME ref = xd->mode_info_context->mbmi.ref_frame;

+              xd->pre.y_buffer = ref_buffer[ref][0] + recon_yoffset;

+              xd->pre.u_buffer = ref_buffer[ref][1] + recon_uvoffset;

+              xd->pre.v_buffer = ref_buffer[ref][2] + recon_uvoffset;

+            } else {

+              // ref_frame is INTRA_FRAME, pre buffer should not be used.

+              xd->pre.y_buffer = 0;

+              xd->pre.u_buffer = 0;

+              xd->pre.v_buffer = 0;

+            }

             /* propagate errors from reference frames */

             xd->corrupted |= ref_fb_corrupted[xd->mode_info_context->mbmi.ref_frame];

-- 

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