lib/, src/: Some empty lists have 0 elements, not 1 empty string

In general, empty fields in a CSV are errors.  However, in some cases,
we want to allow passing empty lists, and the way to encode that is as
an empty string.  This was accidentally broken in 4.17.0, when we
switched from using strtok(3) to strsep(3), without remembering to
special-case an empty CSV.

The bug affected directly groupadd(8) and groupmod(8).

The bug also affected the library function add_groups().  In systems
using PAM, that function is unused.  On systems without PAM, it is
called by the library function setup_uid_gid(), with the contents of the
"CONSOLE_GROUPS" configuration (login.defs) CSV string.

setup_uid_gid() is directly called by su(1) and login(1) on systems
without PAM.

setup_uid_gid() is also called by the library function expire().

expire() is directly called by expiry(1), su(1), and login(1).

This bug is a regression introduced in the release 4.17.0, and present
in the releases 4.17.{0..4} and 4.18.0.

Fixes: 90afe61003ef (2024-12-05; "lib/, src/: Use strsep(3) instead of strtok(3)")
Link: <https://github.com/shadow-maint/shadow/issues/1420>
Reported-by: Osark Vieira <https://github.com/osark084>
Signed-off-by: Alejandro Colomar <alx@kernel.org>

diff --git a/lib/addgrps.c b/lib/addgrps.c
index da7843f23195eaaee893c2c3f7dd1acb26cf4bc8..7768f1325fc050d02335104e2ad816cf24384d53 100644 (file)
--- a/lib/addgrps.c
+++ b/lib/addgrps.c
@@ -24,6 +24,7 @@
 #include "shadow/grp/agetgroups.h"
 #include "shadowlog.h"
 #include "string/strchr/strchrscnt.h"
+#include "string/strcmp/streq.h"
 #include "string/strerrno.h"
 
 
@@ -52,7 +53,7 @@ add_groups(const char *list)
        if (dup == NULL)
                goto free_gids;
 
-       {
+       if (!streq(dup, "")) {
                while (NULL != (g = strsep(&p, ",:"))) {
                        struct group  *grp;
 

diff --git a/src/groupadd.c b/src/groupadd.c
index 7bb946b3c108cff4e264d3bf94e8409f6e5f7310..fab8111b4a9f944ddc5582316bb70e5beec72d56 100644 (file)
--- a/src/groupadd.c
+++ b/src/groupadd.c
@@ -40,6 +40,7 @@
 #include "shadow/gshadow/sgrp.h"
 #include "shadowlog.h"
 #include "string/memset/memzero.h"
+#include "string/strcmp/streq.h"
 #include "string/strerrno.h"
 #include "string/strtok/stpsep.h"
 
@@ -217,7 +218,7 @@ grp_update(void)
        }
 #endif                         /* SHADOWGRP */
 
-       if (user_list) {
+       if (user_list && !streq(user_list, "")) {
                char  *u, *ul;
 
                ul = user_list;

diff --git a/src/groupmod.c b/src/groupmod.c
index 4f9c9ea5fd1285909aa08c3fd419788c337f605c..5b90c2342c6fd1e1a624f08e1e8fe8b4f8a0f9bb 100644 (file)
--- a/src/groupmod.c
+++ b/src/groupmod.c
@@ -282,7 +282,7 @@ grp_update(void)
                }
 #endif                         /* SHADOWGRP */
 
-               {
+               if (!streq(user_list, "")) {
                        ul = user_list;
                        while (NULL != (u = strsep(&ul, ","))) {
                                if (prefix_getpwnam(u) == NULL) {