[PATCH] libselinux: selinux_check_access: fail cleanly if avc_open() failed

avc_init_once() calls avc_open() but discards a failure result, and a
subsequent selinux_check_access() proceeds to avc_context_to_sid()
which now hits assert(avc_running) and aborts the caller.

Latch the initializer outcome and have selinux_check_access() return
-1/EINVAL when the AVC never came up, so callers see an error rather
than a SIGABRT.

Signed-off-by: Stephen Smalley <[email protected]>
---
 libselinux/src/checkAccess.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/libselinux/src/checkAccess.c b/libselinux/src/checkAccess.c
index d8f485e9..3cdd2413 100644
--- a/libselinux/src/checkAccess.c
+++ b/libselinux/src/checkAccess.c
@@ -9,14 +9,13 @@
 
 static pthread_once_t once = PTHREAD_ONCE_INIT;
 static int selinux_enabled;
+static int avc_ok;
 
 static void avc_init_once(void)
 {
 	selinux_enabled = is_selinux_enabled();
-	if (selinux_enabled == 1) {
-		if (avc_open(NULL, 0))
-			return;
-	}
+	if (selinux_enabled == 1 && avc_open(NULL, 0) == 0)
+		avc_ok = 1;
 }
 
 int selinux_check_access(const char *scon, const char *tcon, const char *class,
@@ -33,6 +32,11 @@ int selinux_check_access(const char *scon, const char *tcon, const char *class,
 	if (selinux_enabled != 1)
 		return 0;
 
+	if (!avc_ok) {
+		errno = EINVAL;
+		return -1;
+	}
+
 	rc = avc_context_to_sid(scon, &scon_id);
 	if (rc < 0)
 		return rc;
-- 
2.55.0