[lxc-devel] [lxc/master] cgroups: fix "uninitialized transient_len" warning

[cyphar on Github]

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From 346830421a968c41e3198ca64ab3f7217075e491 Mon Sep 17 00:00:00 2001
From: Aleksa Sarai <cyphar at cyphar.com>
Date: Thu, 2 Apr 2020 19:15:11 +1100
Subject: [PATCH] cgroups: fix "uninitialized transient_len" warning

Without this change, a build error is triggered if you compile with
-Werror=maybe-uninitialized.

 cgroups/cgfsng.c: In function 'cgfsng_monitor_enter':
 groups/cgfsng.c:1387:9: error: 'transient_len' may be used uninitialized in this function
    ret = lxc_writeat(h->cgfd_mon, "cgroup.procs", transient, transient_len);
          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The issue is that if handler->transient_pid is 0, then transient_len is
uninitialised but lxc_writeat(..., transient_len) still gets called.

Signed-off-by: Aleksa Sarai <cyphar at cyphar.com>
---
 src/lxc/cgroups/cgfsng.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/lxc/cgroups/cgfsng.c b/src/lxc/cgroups/cgfsng.c
index 564400221f..21c2c3f7ce 100644
--- a/src/lxc/cgroups/cgfsng.c
+++ b/src/lxc/cgroups/cgfsng.c
@@ -1388,7 +1388,7 @@ __cgfsng_ops static bool cgfsng_monitor_enter(struct cgroup_ops *ops,
 		if (ret)
 			return log_error_errno(false, errno, "Failed to enter cgroup \"%s\"", h->monitor_full_path);
 
-                if (handler->transient_pid < 0)
+		if (handler->transient_pid <= 0)
 			return true;
 
 		ret = lxc_writeat(h->cgfd_mon, "cgroup.procs", transient, transient_len);