avcodec/exr: Allow duplicate use of channel indexes

Fixes: Ticket #8203

Reported-by: durandal_1707
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/exr.c

@@ -1307,6 +1307,7 @@ static int decode_header(EXRContext *s, AVFrame *frame)
     int magic_number, version, i, flags, sar = 0;
     int layer_match = 0;
     int ret;
+    int dup_channels = 0;
 
     s->current_channel_offset = 0;
     s->xmin               = ~0;
@@ -1465,11 +1466,13 @@ static int decode_header(EXRContext *s, AVFrame *frame)
                     s->pixel_type                     = current_pixel_type;
                     s->channel_offsets[channel_index] = s->current_channel_offset;
                 } else if (channel_index >= 0) {
-                    av_log(s->avctx, AV_LOG_ERROR,
+                    av_log(s->avctx, AV_LOG_WARNING,
                             "Multiple channels with index %d.\n", channel_index);
+                    if (++dup_channels > 10) {
                         ret = AVERROR_INVALIDDATA;
                         goto fail;
                     }
+                }
 
                 s->channels = av_realloc(s->channels,
                                          ++s->nb_channels * sizeof(EXRChannel));