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avaudenc: fix crash in avenc_ac3 if input buffers are insufficiently aligned

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Memcpy if needed to ensure sufficient alignment, as some
SIMD instructions might require more alignment than we provide
by default (e.g. vmovaps requires 32 bytes, but gstreamer uses
malloc alignment by default which is 16 bytes here on x86_64).
And in any case buffers might be trimmed, so the only alignment
we can expect is sample frame alignment which might be even
smaller than 16 bytes.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/8318>
This commit is contained in:
Tim-Philipp Müller 2025-01-19 14:29:33 +00:00 committed by GStreamer Marge Bot
parent 289f63b6e7
commit 9b536630f1
1 changed files with 26 additions and 1 deletions
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25
subprojects/gst-libav/ext/libav/gstavaudenc.c
View file

@ -31,6 +31,7 @@
#include <errno.h>
#include <libavcodec/avcodec.h>
#include <libavutil/cpu.h>
#include <libavutil/opt.h>
#include <gst/gst.h>
@ -48,6 +49,8 @@ enum
PROP_CFG_BASE,
};
GST_DEBUG_CATEGORY_STATIC (GST_CAT_PERFORMANCE);
static void gst_ffmpegaudenc_class_init (GstFFMpegAudEncClass * klass);
static void gst_ffmpegaudenc_base_init (GstFFMpegAudEncClass * klass);
static void gst_ffmpegaudenc_init (GstFFMpegAudEnc * ffmpegaudenc);
@ -150,6 +153,8 @@ gst_ffmpegaudenc_class_init (GstFFMpegAudEncClass * klass)
GST_DEBUG_FUNCPTR (gst_ffmpegaudenc_set_format);
gstaudioencoder_class->handle_frame =
GST_DEBUG_FUNCPTR (gst_ffmpegaudenc_handle_frame);
GST_DEBUG_CATEGORY_GET (GST_CAT_PERFORMANCE, "GST_PERFORMANCE");
}
static void
@ -517,7 +522,27 @@ gst_ffmpegaudenc_send_frame (GstFFMpegAudEnc * ffmpegaudenc, GstBuffer * buffer)
gst_buffer_unref (buffer);
buffer_info->buffer = NULL;
} else {
// This is the worst case requirement. It might be possible to query the
// specific alignment requirement for the encoder and transforms in use.
size_t min_align = av_cpu_max_align ();
if (((size_t) audio_in & (min_align - 1)) == 0) {
frame->data[0] = audio_in;
} else {
GST_CAT_TRACE_OBJECT (GST_CAT_PERFORMANCE, ffmpegaudenc,
"Copying input data at %p to ensure minimum alignment of %zu bytes",
audio_in, min_align);
buffer_info->ext_data = av_memdup (audio_in, in_size);
frame->data[0] = buffer_info->ext_data;
// Todo: could probably avoid the buffer_info helper struct allocation
// in this case (and above too)
gst_buffer_unmap (buffer, &buffer_info->map);
gst_buffer_unref (buffer);
buffer_info->buffer = NULL;
}
frame->extended_data = frame->data;
frame->linesize[0] = in_size;
frame->nb_samples = nsamples = in_size / info->bpf;