4.14-stable review patch. If anyone has any objections, please let me know.
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From: Eric Biggers ebiggers@google.com
commit 18026d866801d0c52e5550210563222bd6c7191d upstream.
keyctl_restrict_keyring() allows through a NULL restriction when the "type" is non-NULL, which causes a NULL pointer dereference in asymmetric_lookup_restriction() when it calls strcmp() on the restriction string.
But no key types actually use a "NULL restriction" to mean anything, so update keyctl_restrict_keyring() to reject it with EINVAL.
Reported-by: syzbot syzkaller@googlegroups.com Fixes: 97d3aa0f3134 ("KEYS: Add a lookup_restriction function for the asymmetric key type") Signed-off-by: Eric Biggers ebiggers@google.com Signed-off-by: David Howells dhowells@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- security/keys/keyctl.c | 24 ++++++++++-------------- 1 file changed, 10 insertions(+), 14 deletions(-)
--- a/security/keys/keyctl.c +++ b/security/keys/keyctl.c @@ -1588,9 +1588,8 @@ error_keyring: * The caller must have Setattr permission to change keyring restrictions. * * The requested type name may be a NULL pointer to reject all attempts - * to link to the keyring. If _type is non-NULL, _restriction can be - * NULL or a pointer to a string describing the restriction. If _type is - * NULL, _restriction must also be NULL. + * to link to the keyring. In this case, _restriction must also be NULL. + * Otherwise, both _type and _restriction must be non-NULL. * * Returns 0 if successful. */ @@ -1598,7 +1597,6 @@ long keyctl_restrict_keyring(key_serial_ const char __user *_restriction) { key_ref_t key_ref; - bool link_reject = !_type; char type[32]; char *restriction = NULL; long ret; @@ -1607,31 +1605,29 @@ long keyctl_restrict_keyring(key_serial_ if (IS_ERR(key_ref)) return PTR_ERR(key_ref);
+ ret = -EINVAL; if (_type) { + if (!_restriction) + goto error; + ret = key_get_type_from_user(type, _type, sizeof(type)); if (ret < 0) goto error; - } - - if (_restriction) { - if (!_type) { - ret = -EINVAL; - goto error; - }
restriction = strndup_user(_restriction, PAGE_SIZE); if (IS_ERR(restriction)) { ret = PTR_ERR(restriction); goto error; } + } else { + if (_restriction) + goto error; }
- ret = keyring_restrict(key_ref, link_reject ? NULL : type, restriction); + ret = keyring_restrict(key_ref, _type ? type : NULL, restriction); kfree(restriction); - error: key_ref_put(key_ref); - return ret; }