From 134a3099ea5bb3d13126321ac48bfc48c72784ed Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Thu, 8 Jun 2017 14:48:40 +0100 Subject: [PATCH] KEYS: fix dereferencing NULL payload with nonzero length 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. Signed-off-by: Eric Biggers Signed-off-by: David Howells Signed-off-by: James Morris [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings --- security/keys/keyctl.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c index b9073ebd0817..41525338aa8d 100644 --- a/security/keys/keyctl.c +++ b/security/keys/keyctl.c @@ -85,7 +85,7 @@ SYSCALL_DEFINE5(add_key, const char __user *, _type, payload = NULL; vm = false; - if (_payload) { + if (plen) { ret = -ENOMEM; payload = kmalloc(plen, GFP_KERNEL); if (!payload) { @@ -319,7 +319,7 @@ 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) -- 2.39.2