lkml.org 
[lkml]   [2017]   [Nov]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 3.10 023/139] KEYS: fix dereferencing NULL payload with nonzero length
Date
From: Eric Biggers <ebiggers@google.com>

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.

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>
Signed-off-by: Willy Tarreau <w@1wt.eu>
---
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 066baa1..7576f49 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -93,7 +93,7 @@ SYSCALL_DEFINE5(add_key, const char __user *, _type,
payload = NULL;

vm = false;
- 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)
--
2.8.0.rc2.1.gbe9624a
\
 
 \ /
  Last update: 2017-11-01 22:27    [W:0.374 / U:0.076 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site