73e58adc6b
This fix addresses an issue in is_valid_user_list() where the free
operation was attempted on an address not allocated with malloc(). By
duplicating the pointer with xstrdup(users) into dup, and using dup as
the original pointer, we ensure that only the valid pointer is freed,
avoiding an invalid free operation.
This bug was introduced when changing some code that used strchrnul(3)
to use strsep(3) instead. strsep(3) advances the pointer, unlike the
previous code.
This unconditionally leads to a bug:
- Passing NULL to free(3), if the last field in the
colon-separated-value list is non-empty. This results in a memory
leak.
- Passing a pointer to the null byte ('\0') that terminates the string,
if the last element of the colon-separated-value list is empty. The
most obvious reproducer of such a bogus free(3) call is:
free(strdup("foo:") + 4);
This results in Undefined Behavior, and could result in allocator
data corruption.
Fixes: 16cb664865 (2024-07-01, "lib/, src/: Use strsep(3) instead of its pattern")
Suggested-by: <https://github.com/frostb1ten>
Reported-by: <https://github.com/frostb1ten>
Reviewed-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: Alejandro Colomar <alx@kernel.org>
Cc: Iker Pedrosa <ipedrosa@redhat.com>
Cc: Christian Brauner <christian@brauner.io>
shadow-utils
Introduction
The shadow-utils package includes the necessary programs for converting UNIX password files to the shadow password format, plus programs for managing user and group accounts. The pwconv command converts passwords to the shadow password format. The pwunconv command unconverts shadow passwords and generates a passwd file (a standard UNIX password file). The pwck command checks the integrity of password and shadow files. The lastlog command prints out the last login times for all users. The useradd, userdel, and usermod commands are used for managing user accounts. The groupadd, groupdel, and groupmod commands are used for managing group accounts.
Sites
Code
The main development branch is at https://github.com/shadow-maint/shadow.git
See STABLE.md for a list of supported stable branches.
Contacts
There are several ways to contact us:
- the general discussion mailing list
- the #shadow IRC channel on libera.chat:
- irc://irc.libera.chat/shadow
Mailing archives
- the general discussion mailing list archive
- the commit mailing list archive, only used for historical purposes
Contributions
Contributions are welcome. Follow the guidelines before posting any patches.
Authors and maintainers
Authors and maintainers are listed in AUTHORS.md.