In FreeBSD 12.2-STABLE before r368969, 11.4-STABLE before r369047, 12.2-RELEASE before p3, 12.1-RELEASE before p13 and 11.4-RELEASE before p7 several file systems were not properly initializing the d_off field of the dirent structures returned by VOP_READDIR. In particular, tmpfs(5), smbfs(5), autofs(5) and mqueuefs(5) were failing to do so. As a result, eight uninitialized kernel stack bytes may be leaked to userspace by these file systems.
Weakness
The product does not initialize or incorrectly initializes a resource, which might leave the resource in an unexpected state when it is accessed or used.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Freebsd | Freebsd | 11.4 (including) | 11.4 (including) |
| Freebsd | Freebsd | 11.4-p1 (including) | 11.4-p1 (including) |
| Freebsd | Freebsd | 11.4-p2 (including) | 11.4-p2 (including) |
| Freebsd | Freebsd | 11.4-p3 (including) | 11.4-p3 (including) |
| Freebsd | Freebsd | 11.4-p4 (including) | 11.4-p4 (including) |
| Freebsd | Freebsd | 11.4-p5 (including) | 11.4-p5 (including) |
| Freebsd | Freebsd | 11.4-p6 (including) | 11.4-p6 (including) |
| Freebsd | Freebsd | 12.1 (including) | 12.1 (including) |
| Freebsd | Freebsd | 12.1-p1 (including) | 12.1-p1 (including) |
| Freebsd | Freebsd | 12.1-p10 (including) | 12.1-p10 (including) |
| Freebsd | Freebsd | 12.1-p11 (including) | 12.1-p11 (including) |
| Freebsd | Freebsd | 12.1-p12 (including) | 12.1-p12 (including) |
| Freebsd | Freebsd | 12.1-p2 (including) | 12.1-p2 (including) |
| Freebsd | Freebsd | 12.1-p3 (including) | 12.1-p3 (including) |
| Freebsd | Freebsd | 12.1-p4 (including) | 12.1-p4 (including) |
| Freebsd | Freebsd | 12.1-p5 (including) | 12.1-p5 (including) |
| Freebsd | Freebsd | 12.1-p6 (including) | 12.1-p6 (including) |
| Freebsd | Freebsd | 12.1-p7 (including) | 12.1-p7 (including) |
| Freebsd | Freebsd | 12.1-p8 (including) | 12.1-p8 (including) |
| Freebsd | Freebsd | 12.1-p9 (including) | 12.1-p9 (including) |
| Freebsd | Freebsd | 12.2 (including) | 12.2 (including) |
| Freebsd | Freebsd | 12.2-p1 (including) | 12.2-p1 (including) |
| Freebsd | Freebsd | 12.2-p2 (including) | 12.2-p2 (including) |
Potential Mitigations
- Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
- For example, in Java, if the programmer does not explicitly initialize a variable, then the code could produce a compile-time error (if the variable is local) or automatically initialize the variable to the default value for the variable’s type. In Perl, if explicit initialization is not performed, then a default value of undef is assigned, which is interpreted as 0, false, or an equivalent value depending on the context in which the variable is accessed.