From 23138ead270045f1b3e912e667967b6094244999 Mon Sep 17 00:00:00 2001
From: Richard Guy Briggs <rgb@redhat.com>
Date: Wed, 21 Feb 2018 04:30:07 -0500
Subject: [PATCH] audit: return on memory error to avoid null pointer dereference
Git-commit: 23138ead270045f1b3e912e667967b6094244999
Patch-mainline: v4.17-rc1
References: bsc#1051510

If there is a memory allocation error when trying to change an audit
kernel feature value, the ignored allocation error will trigger a NULL
pointer dereference oops on subsequent use of that pointer.  Return
instead.

Passes audit-testsuite.
See: https://github.com/linux-audit/audit-kernel/issues/76

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
[pm: not necessary (other funcs check for NULL), but a good practice]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 kernel/audit.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/audit.c b/kernel/audit.c
index 5c2544984375..2de74be7cef5 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -1059,6 +1059,8 @@ static void audit_log_feature_change(int which, u32 old_feature, u32 new_feature
 		return;
 
 	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_FEATURE_CHANGE);
+	if (!ab)
+		return;
 	audit_log_task_info(ab, current);
 	audit_log_format(ab, " feature=%s old=%u new=%u old_lock=%u new_lock=%u res=%d",
 			 audit_feature_names[which], !!old_feature, !!new_feature,
-- 
2.18.0