KEYS: DH: don't feed uninitialized "otherinfo" into KDF

If userspace called KEYCTL_DH_COMPUTE with kdf_params containing NULL otherinfo but nonzero otherinfolen, the kernel would allocate a buffer for the otherinfo, then feed it into the KDF without initializing it. Fix this by always doing the copy from userspace (which will fail with EFAULT in this scenario). Signed-off-by: Eric Biggers <[email protected]> Signed-off-by: David Howells <[email protected]> Acked-by: Stephan Mueller <[email protected]> Signed-off-by: James Morris <[email protected]>
ambv · Jun 9, 2017 · 281590b · 281590b
1 parent bbe2404
commit 281590b
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/security/keys/dh.c b/security/keys/dh.c
@@ -317,7 +317,7 @@ long __keyctl_dh_compute(struct keyctl_dh_params __user *params,
 	 * Concatenate SP800-56A otherinfo past DH shared secret -- the
 	 * input to the KDF is (DH shared secret || otherinfo)
 	 */
-	if (kdfcopy && kdfcopy->otherinfo &&
+	if (kdfcopy &&
 	    copy_from_user(kbuf + resultlen, kdfcopy->otherinfo,
 			   kdfcopy->otherinfolen) != 0) {
 		ret = -EFAULT;