[alsa-devel] [PATCH 2/2] snd_pcm_direct_parse_open_conf(): use thread-safe getgrnam_r()

[Jerome Forissier]

Fixes a thread safety issue with snd_pcm_open().

Signed-off-by: Jerome Forissier <jerome at taodyne.com>
---
 src/pcm/pcm_direct.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/src/pcm/pcm_direct.c b/src/pcm/pcm_direct.c
index 6802ecc..38c6c66 100644
--- a/src/pcm/pcm_direct.c
+++ b/src/pcm/pcm_direct.c
@@ -1629,13 +1629,20 @@ int snd_pcm_direct_parse_open_conf(snd_config_t *root, snd_config_t *conf,
 				continue;
 			}
 			if (isdigit(*group) == 0) {
-				struct group *grp = getgrnam(group);
-				if (grp == NULL) {
+				long clen = sysconf(_SC_GETGR_R_SIZE_MAX);
+				size_t len = (clen == -1) ? 1024 : (size_t)clen;
+				struct group grp, *pgrp;
+				char *buffer = (char *)malloc(len);
+				if (buffer == NULL)
+					return -ENOMEM;
+				int st = getgrnam_r(group, &grp, buffer, len, &pgrp);
+				if (st != 0) {
 					SNDERR("The field ipc_gid must be a valid group (create group %s)", group);
-					free(group);
+					free(buffer);
 					return -EINVAL;
 				}
-				rec->ipc_gid = grp->gr_gid;
+				rec->ipc_gid = pgrp->gr_gid;
+				free(buffer);
 			} else {
 				rec->ipc_gid = strtol(group, &endp, 10);
 			}
-- 
1.8.1.2