From 0506b18a3655562ad32ee279ba394f9869faf995 Mon Sep 17 00:00:00 2001
From: Tom Cherry <tomcherry@google.com>
Date: Thu, 23 Feb 2017 13:46:09 -0800
Subject: [PATCH] Check setegid() return values

The clang static analyzer is complaining that we are not checking the
setegid() return value, so let's add these checks.  We should never
fail to return to AID_ROOT, so fail hard in this case.

Bug: 26962034
Test: Boot bullhead
Test: export WITH_STATIC_ANALYZER=1 and run 'mm' in the project directory
Change-Id: I62e95b045c5734305c71502871b6cf17f152edbc
---
 init/devices.cpp | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/init/devices.cpp b/init/devices.cpp
index 5f54ff8fd..bd11f5fa4 100644
--- a/init/devices.cpp
+++ b/init/devices.cpp
@@ -251,7 +251,10 @@ static void make_device(const char *path,
      * some device nodes, so the uid has to be set with chown() and is still
      * racy. Fixing the gid race at least fixed the issue with system_server
      * opening dynamic input devices under the AID_INPUT gid. */
-    setegid(gid);
+    if (setegid(gid)) {
+        PLOG(ERROR) << "setegid(" << gid << ") for " << path << " device failed";
+        goto out;
+    }
     /* If the node already exists update its SELinux label to handle cases when
      * it was created with the wrong context during coldboot procedure. */
     if (mknod(path, mode, dev) && (errno == EEXIST) && secontext) {
@@ -273,7 +276,9 @@ static void make_device(const char *path,
 
 out:
     chown(path, uid, -1);
-    setegid(AID_ROOT);
+    if (setegid(AID_ROOT)) {
+        PLOG(FATAL) << "setegid(AID_ROOT) failed";
+    }
 
     if (secontext) {
         freecon(secontext);