KEYS: prevent NULL pointer dereference in find_asymmetric_key()

In find_asymmetric_key(), if all NULLs are passed in the id_{0,1,2}
arguments, the kernel will first emit WARN but then have an oops
because id_2 gets dereferenced anyway.

Add the missing id_2 check and move WARN_ON() to the final else branch
to avoid duplicate NULL checks.

Found by Linux Verification Center (linuxtesting.org) with Svace static
analysis tool.

Cc: stable@vger.kernel.org # v5.17+
Fixes: 7d30198ee24f ("keys: X.509 public key issuer lookup without AKID")
Suggested-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Roman Smirnov <r.smirnov@omp.ru>
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

diff --git a/crypto/asymmetric_keys/asymmetric_type.c b/crypto/asymmetric_keys/asymmetric_type.c
index a5da8ccd353ef75c5e88e12b06dba8ea87f2f3eb..43af5fa510c09f1611a6b41e788c17469b517f0d 100644 (file)
--- a/crypto/asymmetric_keys/asymmetric_type.c
+++ b/crypto/asymmetric_keys/asymmetric_type.c
@@ -60,17 +60,18 @@ struct key *find_asymmetric_key(struct key *keyring,
        char *req, *p;
        int len;
 
-       WARN_ON(!id_0 && !id_1 && !id_2);
-
        if (id_0) {
                lookup = id_0->data;
                len = id_0->len;
        } else if (id_1) {
                lookup = id_1->data;
                len = id_1->len;
-       } else {
+       } else if (id_2) {
                lookup = id_2->data;
                len = id_2->len;
+       } else {
+               WARN_ON(1);
+               return ERR_PTR(-EINVAL);
        }
 
        /* Construct an identifier "id:<keyid>". */