From c9f838d104fed6f2f61d68164712e3204bf5271b Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Tue, 18 Apr 2017 15:31:09 +0100 Subject: KEYS: fix keyctl_set_reqkey_keyring() to not leak thread keyrings This fixes CVE-2017-7472. Running the following program as an unprivileged user exhausts kernel memory by leaking thread keyrings: #include int main() { for (;;) keyctl_set_reqkey_keyring(KEY_REQKEY_DEFL_THREAD_KEYRING); } Fix it by only creating a new thread keyring if there wasn't one before. To make things more consistent, make install_thread_keyring_to_cred() and install_process_keyring_to_cred() both return 0 if the corresponding keyring is already present. Fixes: d84f4f992cbd ("CRED: Inaugurate COW credentials") Cc: stable@vger.kernel.org # 2.6.29+ Signed-off-by: Eric Biggers Signed-off-by: David Howells --- security/keys/keyctl.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) (limited to 'security/keys/keyctl.c') diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c index ab082a2e8fdd..4ad3212adebe 100644 --- a/security/keys/keyctl.c +++ b/security/keys/keyctl.c @@ -1258,8 +1258,8 @@ error: * Read or set the default keyring in which request_key() will cache keys and * return the old setting. * - * If a process keyring is specified then this will be created if it doesn't - * yet exist. The old setting will be returned if successful. + * If a thread or process keyring is specified then it will be created if it + * doesn't yet exist. The old setting will be returned if successful. */ long keyctl_set_reqkey_keyring(int reqkey_defl) { @@ -1284,11 +1284,8 @@ long keyctl_set_reqkey_keyring(int reqkey_defl) case KEY_REQKEY_DEFL_PROCESS_KEYRING: ret = install_process_keyring_to_cred(new); - if (ret < 0) { - if (ret != -EEXIST) - goto error; - ret = 0; - } + if (ret < 0) + goto error; goto set; case KEY_REQKEY_DEFL_DEFAULT: -- cgit v1.2.3-59-g8ed1b