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libcrun: check setenv failure #2007

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Merged
giuseppe merged 1 commit into from
Mar 16, 2026
+10 −5
Merged

libcrun: check setenv failure #2007

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9 changes: 6 additions & 3 deletions src/libcrun/container.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1176,8 +1176,9 @@ setup_environment (runtime_spec_schema_config_schema *def, uid_t container_uid,
ret = set_home_env (container_uid);
if (UNLIKELY (ret < 0))
{
setenv ("HOME", "/", 1);
libcrun_warning ("cannot detect HOME environment variable, setting default");
if (UNLIKELY (setenv ("HOME", "/", 1) < 0))
return crun_make_error (err, errno, "setenv HOME");
}
}

Expand Down Expand Up @@ -1402,8 +1403,9 @@ container_init_setup (void *args, pid_t own_pid, char *notify_socket,
/* Set primary process to 1 explicitly if nothing is configured and LISTEN_FD is not set. */
if (entrypoint_args->context->listen_fds > 0 && getenv ("LISTEN_PID") == NULL)
{
setenv ("LISTEN_PID", "1", 1);
libcrun_warning ("setting LISTEN_PID=1 since no previous configuration was found");
if (UNLIKELY (setenv ("LISTEN_PID", "1", 1) < 0))
return crun_make_error (err, errno, "setenv LISTENPID");
}

/* Attempt to chdir immediately here, before doing the setresuid. If we fail here, let's
Expand Down Expand Up @@ -3690,8 +3692,9 @@ exec_process_entrypoint (libcrun_context_t *context,
ret = set_home_env (container_uid);
if (UNLIKELY (ret < 0))
{
setenv ("HOME", "/", 1);
libcrun_warning ("cannot detect HOME environment variable, setting default");
if (UNLIKELY (setenv ("HOME", "/", 1) < 0))
return crun_make_error (err, errno, "setenv HOME");
}
}

Expand Down
6 changes: 4 additions & 2 deletions src/libcrun/utils.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1482,8 +1482,10 @@ set_home_env (uid_t id)

if (ret_pw && ret_pw->pw_uid == id)
{
setenv ("HOME", ret_pw->pw_dir, 1);
return 0;
if (UNLIKELY (setenv ("HOME", ret_pw->pw_dir, 1) < 0))
OOM ();
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@giuseppe giuseppe Mar 9, 2026

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can we just set errno and return -1 here?

We may look at better error reporting later, but OOM seems overkill here

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@kolyshkin kolyshkin Mar 11, 2026

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setenv can fail for two reasons: EINVAL (when name is null, or empty, or contains =, which is not the case with $HOME), and ENOMEM. From the quick glance into glibc's stdlib/setenv.c it seems to be true, so OOM seems legit here.

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@kolyshkin kolyshkin Mar 11, 2026

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The above theoretically means we can OOM() in other places after setenv failed, if its first argument is known to be good. Practically, I'm not sure since non-glibc implementations can possibly return other errors (although looking into current musl sources, it's the same as for glibc).

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@giuseppe giuseppe Mar 12, 2026

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ok that is good, OOM looks correct. Thanks!

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@eriksjolund eriksjolund Mar 12, 2026

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I haven't had time to look into this, but my original idea by using OOM() was to avoid that
the environment variable HOME is set to / because the system is low on memory, for example here

crun/src/libcrun/container.c

Lines 3690 to 3696 in c07aadc

ret = set_home_env (container_uid);
if (UNLIKELY (ret < 0))
{
setenv ("HOME", "/", 1);
libcrun_warning ("cannot detect HOME environment variable, setting default");
}
}

Thinking more about it, a similar problem could occur if fopen() fails with ENFILE here

crun/src/libcrun/utils.c

Lines 1457 to 1459 in c07aadc

stream = fopen ("/etc/passwd", "re");
if (stream == NULL)
return -1;

Maybe set_home_env() should take an err argument so that it is possible for the caller to differentiate between

  • no. home path was found in /etc/passwd
  • some other problems occured (for instance ENFILE or ENOMEM)

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@kolyshkin kolyshkin Mar 12, 2026

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@eriksjolund this sounds good to me. I'm going to merge this PR as is though, as it fixes the issue #1998.

Feel free to a new PR, improving set_home_env error reporting.

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@kolyshkin kolyshkin Mar 12, 2026

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... and also calling OOM in case setenv failed, in other places, like suggested above.

else
return 0;
}
}
}
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