[PATCH 4.16 239/272] audit: return on memory error to avoid null pointer dereference

Greg Kroah-Hartman
2018-05-28T11:18:52Z

From: Richard Guy Briggs <rgb@redhat.com>

[ Upstream commit 23138ead270045f1b3e912e667967b6094244999 ]

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>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/audit.c | 2 ++
1 file changed, 2 insertions(+)

--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -1058,6 +1058,8 @@ static void audit_log_feature_change(int
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,