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From 0d0ba7ee44d652c23e6027fe3b1c1ee8e2f65a25 Mon Sep 17 00:00:00 2001
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From: systemd team <systemd-maint@redhat.com>
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Date: Mon, 19 Aug 2019 13:51:48 +0200
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Subject: [PATCH] Call getgroups() to know size of supplementary groups array
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 to allocate
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Resolves RHBZ #1743230 - journalctl dumps core when stack limit is reduced to 256 KB
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---
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 src/shared/util.c | 13 ++++++++-----
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 1 file changed, 8 insertions(+), 5 deletions(-)
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diff --git a/src/shared/util.c b/src/shared/util.c
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index 127a64c3c6..ce6678eb38 100644
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--- a/src/shared/util.c
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+++ b/src/shared/util.c
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@@ -5097,7 +5097,7 @@ int get_group_creds(const char **groupname, gid_t *gid) {
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 int in_gid(gid_t gid) {
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         gid_t *gids;
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-        int ngroups_max, r, i;
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+        int ngroups, r, i;
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         if (getgid() == gid)
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                 return 1;
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@@ -5105,12 +5105,15 @@ int in_gid(gid_t gid) {
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         if (getegid() == gid)
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                 return 1;
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-        ngroups_max = sysconf(_SC_NGROUPS_MAX);
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-        assert(ngroups_max > 0);
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+        ngroups = getgroups(0, NULL);
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+        if (ngroups < 0)
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+                return -errno;
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+        if (ngroups == 0)
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+                return 0;
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-        gids = alloca(sizeof(gid_t) * ngroups_max);
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+        gids = alloca(sizeof(gid_t) * ngroups);
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-        r = getgroups(ngroups_max, gids);
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+        r = getgroups(ngroups, gids);
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         if (r < 0)
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                 return -errno;
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