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usermod: fix segmentation fault on invalid expiration dates #413

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usermod: fix segmentation fault on invalid expiration dates #413

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32 changes: 27 additions & 5 deletions src/usermod.c
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Original file line number Diff line number Diff line change
Expand Up @@ -98,6 +98,7 @@
#define E_SUB_UID_UPDATE 16 /* can't update the subordinate uid file */
#define E_SUB_GID_UPDATE 18 /* can't update the subordinate gid file */
#endif /* ENABLE_SUBIDS */
#define E_BAD_SWFILE 19 /* bad shadow entry */

#define VALID(s) (strcspn (s, ":\n") == strlen (s))

Expand Down Expand Up @@ -184,7 +185,7 @@ static bool sub_gid_locked = false;


/* local function prototypes */
static void date_to_str (/*@unique@*//*@out@*/char *buf, size_t maxsize,
static int date_to_str (/*@unique@*//*@out@*/char *buf, size_t maxsize,
long int date);
static int get_groups (char *);
static /*@noreturn@*/void usage (int status);
Expand Down Expand Up @@ -212,7 +213,7 @@ static void move_mailbox (void);

extern int allow_bad_names;

static void date_to_str (/*@unique@*//*@out@*/char *buf, size_t maxsize,
static int date_to_str (/*@unique@*//*@out@*/char *buf, size_t maxsize,
long int date)
{
struct tm *tp;
Expand All @@ -222,16 +223,21 @@ static void date_to_str (/*@unique@*//*@out@*/char *buf, size_t maxsize,
} else {
time_t t = (time_t) date;
tp = gmtime (&t);
if (tp == NULL)
return -1;
#ifdef HAVE_STRFTIME
strftime (buf, maxsize, "%Y-%m-%d", tp);
#else
(void) snprintf (buf, maxsize, "%04d-%02d-%02d",
int ret = snprintf (buf, maxsize, "%04d-%02d-%02d",
tp->tm_year + 1900,
tp->tm_mon + 1,
tp->tm_mday);
if(ret < 0)
return -1;
#endif /* HAVE_STRFTIME */
}
buf[maxsize - 1] = '\0';
return 0;
}

/*
Expand Down Expand Up @@ -627,10 +633,26 @@ static void new_spent (struct spwd *spent)
if (eflg) {
/* log dates rather than numbers of days. */
char new_exp[16], old_exp[16];
date_to_str (new_exp, sizeof(new_exp),
int ret = date_to_str (new_exp, sizeof(new_exp),
user_newexpire * DAY);
date_to_str (old_exp, sizeof(old_exp),
if (ret < 0)
{
fprintf (stderr,
_("%s: invalid new expiration date '%ld'\n"),
Prog, user_newexpire
);
fail_exit (E_BAD_ARG);
}
ret = date_to_str (old_exp, sizeof(old_exp),
user_expire * DAY);
if (ret < 0)
{
fprintf (stderr,
_("%s: invalid old expiration date '%ld'\n"),
Prog, user_expire
);
fail_exit (E_BAD_SWFILE);
}
#ifdef WITH_AUDIT
audit_logger (AUDIT_USER_CHAUTHTOK, Prog,
"changing expiration date",
Expand Down