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: v3.10.108~118 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f862c9436454a5b78d29ebaebc547aa6d1474f7a;p=thirdparty%2Fkernel%2Fstable.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. Cc: stable@vger.kernel.org # 2.6.10+ Signed-off-by: Eric Biggers Signed-off-by: David Howells Signed-off-by: James Morris Signed-off-by: Willy Tarreau --- diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c index 066baa1926bb8..7576f49eeb345 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)