https://gitlab.freedesktop.org/pipewire/pipewire/-/issues/3600
https://gitlab.freedesktop.org/pipewire/pipewire/-/commit/920beea3eb55ee7156bd8c00a201bdcafa0df5b0

From 920beea3eb55ee7156bd8c00a201bdcafa0df5b0 Mon Sep 17 00:00:00 2001
From: Wim Taymans <wtaymans@redhat.com>
Date: Sun, 22 Oct 2023 17:26:25 +0200
Subject: [PATCH] alsa: guard agaist NULL areas

snd_pcm_ioplug_mmap_areas() can fail and return NULL

Fixes #3600
--- a/pipewire-alsa/alsa-plugins/pcm_pipewire.c
+++ b/pipewire-alsa/alsa-plugins/pcm_pipewire.c
@@ -309,21 +309,21 @@ snd_pcm_pipewire_process(snd_pcm_pipewire_t *pw, struct pw_buffer *b,
 		xfer = nframes;
 		if (xfer > 0) {
 			const snd_pcm_channel_area_t *areas = snd_pcm_ioplug_mmap_areas(io);
-			const snd_pcm_uframes_t offset = hw_ptr % io->buffer_size;
-
-			if (io->stream == SND_PCM_STREAM_PLAYBACK)
-				snd_pcm_areas_copy_wrap(pwareas, 0, nframes,
-						areas, offset,
-						io->buffer_size,
-						io->channels, xfer,
-						io->format);
-			else
-				snd_pcm_areas_copy_wrap(areas, offset,
-						io->buffer_size,
-						pwareas, 0, nframes,
-						io->channels, xfer,
-						io->format);
-
+			if (areas != NULL) {
+				const snd_pcm_uframes_t offset = hw_ptr % io->buffer_size;
+				if (io->stream == SND_PCM_STREAM_PLAYBACK)
+					snd_pcm_areas_copy_wrap(pwareas, 0, nframes,
+							areas, offset,
+							io->buffer_size,
+							io->channels, xfer,
+							io->format);
+				else
+					snd_pcm_areas_copy_wrap(areas, offset,
+							io->buffer_size,
+							pwareas, 0, nframes,
+							io->channels, xfer,
+							io->format);
+			}
 			hw_ptr += xfer;
 			if (hw_ptr >= pw->boundary)
 				hw_ptr -= pw->boundary;
-- 
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