Created attachment 1448305 [details]
the patch

Description of problem:
Pam_mysql segfaults when an encrypted password used and the characters of salt in database not in [a-zA-Z0-9./].

The pam_mysql uses first two characters of the password as salt for crypt functions. However, according to man-page, the salt can only contain these characters: [a-zA-Z0-9./], otherwise it can return null pointer.

The code of checking password (pam_mysql.c) looks like this:
vresult = strcmp(row[0], crypt(passwd, row[0]));

So when the crypt call failed, the row[0] string is compared with null-pointer string and the segfault occurs.

In the one of pam_mysql fork it was fixed in 2015: https://github.com/NigelCunningham/pam-MySQL/commit/af6c8bb9e0375dda6cee20b3de6a23f5d7087635#diff-5903b4d238fdc681232da9aea81f66c3

Version-Release number of selected component (if applicable):
0.7RC1

How reproducible:
The bug is reproducible in rhel6, but not reproducible in rhel5.

Steps to Reproduce:
Setup pam_mysql to use encrypted passwords, create a user with password "!@#$%^" and try to login.

Actual results:
Program segfaults

Expected results:
Program doesn't segfault