From e89d4c97385ff8180e6e81e84c5aa745daf28a79 Mon Sep 17 00:00:00 2001 From: Thorsten Kukuk Date: Mon, 22 Jun 2015 14:53:01 +0200 Subject: Release version 1.2.1 Security fix: CVE-2015-3238 If the process executing pam_sm_authenticate or pam_sm_chauthtok method of pam_unix is not privileged enough to check the password, e.g. if selinux is enabled, the _unix_run_helper_binary function is called. When a long enough password is supplied (16 pages or more, i.e. 65536+ bytes on a system with 4K pages), this helper function hangs indefinitely, blocked in the write(2) call while writing to a blocking pipe that has a limited capacity. With this fix, the verifiable password length will be limited to PAM_MAX_RESP_SIZE bytes (i.e. 512 bytes) for pam_exec and pam_unix. * NEWS: Update * configure.ac: Bump version * modules/pam_exec/pam_exec.8.xml: document limitation of password length * modules/pam_exec/pam_exec.c: limit password length to PAM_MAX_RESP_SIZE * modules/pam_unix/pam_unix.8.xml: document limitation of password length * modules/pam_unix/pam_unix_passwd.c: limit password length * modules/pam_unix/passverify.c: Likewise * modules/pam_unix/passverify.h: Likewise * modules/pam_unix/support.c: Likewise --- modules/pam_unix/support.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'modules/pam_unix/support.c') diff --git a/modules/pam_unix/support.c b/modules/pam_unix/support.c index fdb45c20..abccd828 100644 --- a/modules/pam_unix/support.c +++ b/modules/pam_unix/support.c @@ -609,7 +609,12 @@ static int _unix_run_helper_binary(pam_handle_t *pamh, const char *passwd, /* if the stored password is NULL */ int rc=0; if (passwd != NULL) { /* send the password to the child */ - if (write(fds[1], passwd, strlen(passwd)+1) == -1) { + int len = strlen(passwd); + + if (len > PAM_MAX_RESP_SIZE) + len = PAM_MAX_RESP_SIZE; + if (write(fds[1], passwd, len) == -1 || + write(fds[1], "", 1) == -1) { pam_syslog (pamh, LOG_ERR, "Cannot send password to helper: %m"); retval = PAM_AUTH_ERR; } -- cgit v1.2.3