KEYS: DH: validate __spare field

Syscalls must validate that their reserved arguments are zero and return
EINVAL otherwise.  Otherwise, it will be impossible to actually use them
for anything in the future because existing programs may be passing
garbage in.  This is standard practice when adding new APIs.

Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>

diff --git a/security/keys/compat_dh.c b/security/keys/compat_dh.c
index a6a659b..aa6b34c 100644 (file)
--- a/security/keys/compat_dh.c
+++ b/security/keys/compat_dh.c
@@ -33,6 +33,8 @@ long compat_keyctl_dh_compute(struct keyctl_dh_params __user *params,
        kdfcopy.hashname = compat_ptr(compat_kdfcopy.hashname);
        kdfcopy.otherinfo = compat_ptr(compat_kdfcopy.otherinfo);
        kdfcopy.otherinfolen = compat_kdfcopy.otherinfolen;
+       memcpy(kdfcopy.__spare, compat_kdfcopy.__spare,
+              sizeof(kdfcopy.__spare));
 
        return __keyctl_dh_compute(params, buffer, buflen, &kdfcopy);
 }

diff --git a/security/keys/dh.c b/security/keys/dh.c
index 4755d4b..d1ea9f3 100644 (file)
--- a/security/keys/dh.c
+++ b/security/keys/dh.c
@@ -266,6 +266,11 @@ long __keyctl_dh_compute(struct keyctl_dh_params __user *params,
        if (kdfcopy) {
                char *hashname;
 
+               if (memchr_inv(kdfcopy->__spare, 0, sizeof(kdfcopy->__spare))) {
+                       ret = -EINVAL;
+                       goto out1;
+               }
+
                if (buflen > KEYCTL_KDF_MAX_OUTPUT_LEN ||
                    kdfcopy->otherinfolen > KEYCTL_KDF_MAX_OI_LEN) {
                        ret = -EMSGSIZE;