Patch "KEYS: fix dereferencing NULL payload with nonzero length" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

KEYS: fix dereferencing NULL payload with nonzero length

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
keys-fix-dereferencing-null-payload-with-nonzero-length.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Eric Biggers <[email protected]>
Date: Thu, 8 Jun 2017 14:48:40 +0100
Subject: KEYS: fix dereferencing NULL payload with nonzero length

From: Eric Biggers <[email protected]>

commit 5649645d725c73df4302428ee4e02c869248b4c5 upstream.

sys_add_key() and the KEYCTL_UPDATE operation of sys_keyctl() allowed a NULL payload with nonzero length to be passed to the key type's ->preparse(), ->instantiate(), and/or ->update() methods. Various key types including asymmetric, cifs.idmap, cifs.spnego, and pkcs7_test did not handle this case, allowing an unprivileged user to trivially cause a NULL pointer dereference (kernel oops) if one of these key types was present. Fix it by doing the copy_from_user() when 'plen' is nonzero rather than when '_payload' is non-NULL, causing the syscall to fail with EFAULT as expected when an invalid buffer is specified.

---
 security/keys/keyctl.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

@@ -97,7 +97,7 @@ SYSCALL_DEFINE5(add_key, const char __us
 	/* pull the payload in if one was supplied */
 	payload = NULL;
 
-	if (_payload) {
+	if (plen) {
 		ret = -ENOMEM;
 		payload = kmalloc(plen, GFP_KERNEL | __GFP_NOWARN);
 		if (!payload) {

@@ -327,7 +327,7 @@ long keyctl_update_key(key_serial_t id,
 
 	/* pull the payload in if one was supplied */
 	payload = NULL;
-	if (_payload) {
+	if (plen) {
 		ret = -ENOMEM;
 		payload = kmalloc(plen, GFP_KERNEL);
 		if (!payload)

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/keys-encrypted-avoid-encrypting-decrypting-stack-buffers.patch queue-4.9/keys-fix-freeing-uninitialized-memory-in-key_update.patch queue-4.9/keys-fix-dereferencing-null-payload-with-nonzero-length.patch