apparmor: Fix aa_label_build() error handling for failed merges

aa_label_merge() can return NULL for memory allocations failures
make sure to handle and set the correct error in this case.

Reported-by: Peng Hao <peng.hao2@zte.com.cn>
Signed-off-by: John Johansen <john.johansen@canonical.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c
index 08c88de0ffda..11975ec8d566 100644
--- a/security/apparmor/domain.c
+++ b/security/apparmor/domain.c
@@ -1444,7 +1444,10 @@ check:
                         new = aa_label_merge(label, target, GFP_KERNEL);
                 if (IS_ERR_OR_NULL(new)) {
                         info = "failed to build target label";
-                        error = PTR_ERR(new);
+                        if (!new)
+                                error = -ENOMEM;
+                        else
+                                error = PTR_ERR(new);
                         new = NULL;
                         perms.allow = 0;
                         goto audit;