[FFmpeg-devel] [PATCH 04/25] avfilter/af_headphone: Fix segfault when using very short streams

[Andreas Rheinhardt]

When the headphone filter does its processing in the time domain,
the lengths of the buffers involved are determined by three parameters,
only two of which are relevant here: ir_len and air_len. The former is
the length (in samples) of the longest HRIR input stream and the latter
is the smallest power-of-two bigger than ir_len.

Using optimized functions to calculate the convolution places
restrictions on the alignment of the length of the vectors whose scalar
product is calculated. Therefore said length, namely ir_len, is aligned
on 32; but the number of elements of the buffers used is given by air_len
and for ir_len < 16 a buffer overflow happens.

This commit fixes this by ensuring that air_len is always >= 32 if
processing happens in the time domain.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
---
 libavfilter/af_headphone.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/libavfilter/af_headphone.c b/libavfilter/af_headphone.c
index f488e0e28d..54b5dfec4c 100644
--- a/libavfilter/af_headphone.c
+++ b/libavfilter/af_headphone.c
@@ -405,6 +405,9 @@ static int convert_coeffs(AVFilterContext *ctx, AVFilterLink *inlink)
     int i, j, k;
 
     s->air_len = 1 << (32 - ff_clz(ir_len));
+    if (s->type == TIME_DOMAIN) {
+        s->air_len = FFALIGN(s->air_len, 32);
+    }
     s->buffer_length = 1 << (32 - ff_clz(s->air_len));
     s->n_fft = n_fft = 1 << (32 - ff_clz(ir_len + s->size));
 
-- 
2.20.1