From: Eric Biggers Date: Thu, 8 Jun 2017 13:48:40 +0000 (+0100) Subject: KEYS: fix dereferencing NULL payload with nonzero length X-Git-Tag: v4.9.32~93 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=1b253e023f8f75b109564a61d2050d818f75b4f3;p=platform%2Fkernel%2Flinux-amlogic.git 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 Signed-off-by: Greg Kroah-Hartman --- diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c index dbbfd77..ada12c3 100644 --- a/security/keys/keyctl.c +++ b/security/keys/keyctl.c @@ -97,7 +97,7 @@ SYSCALL_DEFINE5(add_key, const char __user *, _type, /* 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)