Bug 457519

Description of problem:
RHEL 4.7(X86)

If user account over 0x7fffffff gid, groups_search(kernel/sys.c) does not work 
correctly.

ex)
$ whoami
was
$ id
uid=502(was) gid=502(was) groups=502(was),600(oninstall),2151678465
(was2),2151678496(was3)

$ ls -l /tmp
drwxrwx---  2 root     oninstall   4096 Jul 29 13:56 aaa

user "was" have "oninstall" gid and  should be able to access /tmp/aaa
But "was" cannot access /tmp/aaa

$ ls -l /tmp/aaa
ls: /tmp/aaa: Permission denied

As a result of investigation, I think  groups_search() function has a bug.
The argument gid_t grp is unsigned int. However cmp is int. If gid is 
over 0x7fffffff(2147483647), value of cmp will become incorrect value.
As a result, return value will be incorrect(0) also. 

/* a simple bsearch */
int groups_search(struct group_info *group_info, gid_t grp)
{
        int left, right;

        if (!group_info)
                return 0;

        left = 0;
        right = group_info->ngroups;
        while (left < right) {
                int mid = (left+right)/2;
                int cmp = grp - GROUP_AT(group_info, mid);
                if (cmp > 0)
                        left = mid + 1;
                else if (cmp < 0)
                        right = mid;
                else
                        return 1;
        }
        return 0;
}



Version-Release number of selected component (if applicable):


How reproducible:

Steps to Reproduce:

1.  create account and set data to /etc/group so that it have the below gids.

oninstall:x:600:test1,was,test2
was2:x:2151678465:was,test2
was3:x:2151678496:was
was:x:502:

$ id was
uid=502(was) gid=502(was) groups=502(was),600(oninstall),2151678465
(was2),2151678496(was3)

2. #mkdir /tmp/aaa
    #chgrp oninstall /tmp/aaa

3.  # su - was
    [was]$ ls -l /tmp/aaa
    ls: /tmp/aaa: Permission denied
  
Actual results:

ls fail with "Permission denied error"

Expected results:

ls success

Additional info:

I think this can be fixed by attachment way.