audit: return on memory error to avoid null pointer dereference

[ 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>

diff --git a/kernel/audit.c b/kernel/audit.c
index da4e7c0e36f7aac4940a4ef37e86c569a9ed5f32..3461a3d874feda801cef8af5d3b85a54e17187b7 100644 (file)
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -742,6 +742,8 @@ 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,