From: Renaud Métrich <rmetrich@redhat.com>
Date: Fri, 13 Sep 2019 09:18:18 +0000 (+0200)
Subject: Call getgroups() to know size of supplementary groups array to allocate
X-Git-Tag: v244-rc1~303
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=f5e0b942af1e86993c21f4e5c84342bb10403dac;p=thirdparty%2Fsystemd.git

Call getgroups() to know size of supplementary groups array to allocate

Resolves RHBZ #1743230 - journalctl dumps core when stack limit is reduced to 256 KB
---

diff --git a/src/basic/user-util.c b/src/basic/user-util.c
index 3b253bc264d..957285c0914 100644
--- a/src/basic/user-util.c
+++ b/src/basic/user-util.c
@@ -410,9 +410,8 @@ char* gid_to_name(gid_t gid) {
 }
 
 int in_gid(gid_t gid) {
-        long ngroups_max;
         gid_t *gids;
-        int r, i;
+        int ngroups, r, i;
 
         if (getgid() == gid)
                 return 1;
@@ -423,12 +422,15 @@ int in_gid(gid_t gid) {
         if (!gid_is_valid(gid))
                 return -EINVAL;
 
-        ngroups_max = sysconf(_SC_NGROUPS_MAX);
-        assert(ngroups_max > 0);
+        ngroups = getgroups(0, NULL);
+        if (ngroups < 0)
+                return -errno;
+        if (ngroups == 0)
+                return 0;
 
-        gids = newa(gid_t, ngroups_max);
+        gids = newa(gid_t, ngroups);
 
-        r = getgroups(ngroups_max, gids);
+        r = getgroups(ngroups, gids);
         if (r < 0)
                 return -errno;