From: Jaroslav Kysela <perex@perex.cz>
Date: Mon, 25 May 2026 10:34:37 +0000 (+0200)
Subject: pcm: snd_pcm_slave_conf - fix C99 variable-length array allocation
X-Git-Url: https://git.alsa-project.org/?a=commitdiff_plain;h=33c9949e75593c09a5e08fa3f867a0734c8d5ca3;p=alsa-lib.git

pcm: snd_pcm_slave_conf - fix C99 variable-length array allocation

The C standard (C99 §6.7.5.2p1) requires VLA bounds to be greater than zero;
a bound of 0 is undefined behavior. Reported by UBSan.

Fixes: https://github.com/alsa-project/alsa-lib/issues/505
Signed-off-by: Jaroslav Kysela <perex@perex.cz>
---

diff --git a/src/pcm/pcm.c b/src/pcm/pcm.c
index 11b15100..f2831ed7 100644
--- a/src/pcm/pcm.c
+++ b/src/pcm/pcm.c
@@ -7824,7 +7824,7 @@ int snd_pcm_slave_conf(snd_config_t *root, snd_config_t *conf,
 		int flags;
 		void *ptr;
 		int present;
-	} fields[count];
+	} fields[count > 0 ? count : 1];
 	unsigned int k;
 	snd_config_t *pcm_conf = NULL;
 	int err;