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CA-89:01
                                CERT Advisory
                                January 1989
                                Passwd hole
- -----------------------------------------------------------------------------

The CERT center received the following information from Keith Bostic
from the Computer Systems Research Group at UC-Berkeley on Dec. 21, 1988.
This patch has also been posted to comp.bugs.4bsd.ucb-fixes.

Please note that this patch will only work with BSD 4.3.  If you have
4.2 please let me know and I will forward the correct patch.

- -----------------------------------------------------------------------------

Computer Emergency Response Team (CERT)
Software Engineering Institute
Carnegie Mellon University
Pittsburgh, PA 15213-3890

Internet: [email protected]
Telephone: 412-268-7090 24-hour hotline: CERT personnel answer
          7:30a.m.-6:00p.m. EST, on call for
          emergencies other hours.

Past advisories and other information are available for anonymous ftp
from cert.org (192.88.209.5).




Subject: security problem in passwd
Index: bin/passwd.c 4.3BSD

Description:
       There's a security problem associated with the passwd(1)
       program in all known Berkeley systems.  This problem is
       also in most Berkeley derived systems, see your vendor
       for more information.

Fix:
       Apply the following patch to the file src/bin/passwd.c and
       recompile/reinstall it.

*** passwd.c.orig       Wed Dec 21 08:57:41 1988
- --- passwd.c  Wed Dec 21 09:00:25 1988
***************
*** 332,337 ****
- --- 332,339 ----
       return (crypt(pwbuf, saltc));
 }

+ #define       STRSIZE 100
+
 char *
 getloginshell(pwd, u, arg)
       struct passwd *pwd;
***************
*** 338,344 ****
       int u;
       char *arg;
 {
!       static char newshell[BUFSIZ];
       char *cp, *valid, *getusershell();

       if (pwd->pw_shell == 0 || *pwd->pw_shell == '\0')
- --- 340,346 ----
       int u;
       char *arg;
 {
!       static char newshell[STRSIZE];
       char *cp, *valid, *getusershell();

       if (pwd->pw_shell == 0 || *pwd->pw_shell == '\0')
***************
*** 415,423 ****
 getfingerinfo(pwd)
       struct passwd *pwd;
 {
!       char in_str[BUFSIZ];
       struct default_values *defaults, *get_defaults();
!       static char answer[4*BUFSIZ];

       answer[0] = '\0';
       defaults = get_defaults(pwd->pw_gecos);
- --- 417,425 ----
 getfingerinfo(pwd)
       struct passwd *pwd;
 {
!       char in_str[STRSIZE];
       struct default_values *defaults, *get_defaults();
!       static char answer[4*STRSIZE];

       answer[0] = '\0';
       defaults = get_defaults(pwd->pw_gecos);
***************
*** 429,435 ****
        */
       do {
               printf("\nName [%s]: ", defaults->name);
!               (void) fgets(in_str, BUFSIZ, stdin);
               if (special_case(in_str, defaults->name))
                       break;
       } while (illegal_input(in_str));
- --- 431,437 ----
        */
       do {
               printf("\nName [%s]: ", defaults->name);
!               (void) fgets(in_str, STRSIZE, stdin);
               if (special_case(in_str, defaults->name))
                       break;
       } while (illegal_input(in_str));
***************
*** 440,446 ****
       do {
               printf("Room number (Exs: 597E or 197C) [%s]: ",
                       defaults->office_num);
!               (void) fgets(in_str, BUFSIZ, stdin);
               if (special_case(in_str, defaults->office_num))
                       break;
       } while (illegal_input(in_str) || illegal_building(in_str));
- --- 442,448 ----
       do {
               printf("Room number (Exs: 597E or 197C) [%s]: ",
                       defaults->office_num);
!               (void) fgets(in_str, STRSIZE, stdin);
               if (special_case(in_str, defaults->office_num))
                       break;
       } while (illegal_input(in_str) || illegal_building(in_str));
***************
*** 452,458 ****
       do {
               printf("Office Phone (Ex: 6426000) [%s]: ",
                       defaults->office_phone);
!               (void) fgets(in_str, BUFSIZ, stdin);
               if (special_case(in_str, defaults->office_phone))
                       break;
               remove_hyphens(in_str);
- --- 454,460 ----
       do {
               printf("Office Phone (Ex: 6426000) [%s]: ",
                       defaults->office_phone);
!               (void) fgets(in_str, STRSIZE, stdin);
               if (special_case(in_str, defaults->office_phone))
                       break;
               remove_hyphens(in_str);
***************
*** 464,470 ****
        */
       do {
               printf("Home Phone (Ex: 9875432) [%s]: ", defaults->home_phone);
!               (void) fgets(in_str, BUFSIZ, stdin);
               if (special_case(in_str, defaults->home_phone))
                       break;
               remove_hyphens(in_str);
- --- 466,472 ----
        */
       do {
               printf("Home Phone (Ex: 9875432) [%s]: ", defaults->home_phone);
!               (void) fgets(in_str, STRSIZE, stdin);
               if (special_case(in_str, defaults->home_phone))
                       break;
               remove_hyphens(in_str);
***************
*** 501,507 ****
       if (input_str[length-1] != '\n') {
               /* the newline and the '\0' eat up two characters */
               printf("Maximum number of characters allowed is %d\n",
!                       BUFSIZ-2);
               /* flush the rest of the input line */
               while (getchar() != '\n')
                       /* void */;
- --- 503,509 ----
       if (input_str[length-1] != '\n') {
               /* the newline and the '\0' eat up two characters */
               printf("Maximum number of characters allowed is %d\n",
!                       STRSIZE-2);
               /* flush the rest of the input line */
               while (getchar() != '\n')
                       /* void */;

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