From b22332dd4f0042e9fc7248aa918b991d684d8f28 Mon Sep 17 00:00:00 2001
From: Sami Kerola
Date: Sun, 13 Jan 2019 19:48:59 +0000
Subject: last: fix wtmp user name buffer overflow [asan]

Ensure utmp user name field is null terminated.  Without that getpwnam() can
buffer overflow, when wtmp file is malformed.

Addresses: https://github.com/karelzak/util-linux/issues/715
Signed-off-by: Sami Kerola <kerolasa@iki.fi>
---
 login-utils/last.c | 1 +
 1 file changed, 1 insertion(+)

(limited to 'login-utils')

diff --git a/login-utils/last.c b/login-utils/last.c
index 6b25efd4c..be744b079 100644
--- a/login-utils/last.c
+++ b/login-utils/last.c
@@ -600,6 +600,7 @@ static int is_phantom(const struct last_control *ctl, struct utmpx *ut)
 
 	if (ut->ut_tv.tv_sec < ctl->boot_time.tv_sec)
 		return 1;
+	ut->ut_user[__UT_NAMESIZE - 1] = '\0';
 	pw = getpwnam(ut->ut_user);
 	if (!pw)
 		return 1;
-- 
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