The product calls umask() with an incorrect argument that is specified as if it is an argument to chmod().
Time of Introduction
Implementation
Applicable Platforms
Languages
C
Common Consequences
Scope
Effect
Confidentiality
Integrity
Access Control
Technical Impact: Read files or
directories; Modify files or
directories; Bypass protection
mechanism
Potential Mitigations
Use umask() with the correct argument.
If you suspect misuse of umask(), you can use grep to spot call
instances of umask().
Other Notes
The umask() man page begins with the false statement: "umask sets the
umask to mask & 0777" Although this behavior would better align with the
usage of chmod(), where the user provided argument specifies the bits to
enable on the specified file, the behavior of umask() is in fact opposite:
umask() sets the umask to ~mask & 0777. The umask() man page goes on to
describe the correct usage of umask(): "The umask is used by open() to set
initial file permissions on a newly-created file. Specifically, permissions
in the umask are turned off from the mode argument to open(2) (so, for
example, the common umask default value of 022 results in new files being
created with permissions 0666 & ~022 = 0644 = rw-r--r-- in the usual
case where the mode is specified as 0666)."
Description
