In FreeBSD 12.1-STABLE before r364644, 11.4-STABLE before r364651, 12.1-RELEASE before p9, 11.4-RELEASE before p3, and 11.3-RELEASE before p13, improper handling in the kernel causes a use-after-free bug by sending large user messages from multiple threads on the same SCTP socket. The use-after-free situation may result in unintended kernel behaviour including a kernel panic.
Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Freebsd | Freebsd | 11.3 (including) | 11.3 (including) |
| Freebsd | Freebsd | 11.3-p1 (including) | 11.3-p1 (including) |
| Freebsd | Freebsd | 11.3-p10 (including) | 11.3-p10 (including) |
| Freebsd | Freebsd | 11.3-p11 (including) | 11.3-p11 (including) |
| Freebsd | Freebsd | 11.3-p12 (including) | 11.3-p12 (including) |
| Freebsd | Freebsd | 11.3-p2 (including) | 11.3-p2 (including) |
| Freebsd | Freebsd | 11.3-p3 (including) | 11.3-p3 (including) |
| Freebsd | Freebsd | 11.3-p4 (including) | 11.3-p4 (including) |
| Freebsd | Freebsd | 11.3-p5 (including) | 11.3-p5 (including) |
| Freebsd | Freebsd | 11.3-p6 (including) | 11.3-p6 (including) |
| Freebsd | Freebsd | 11.3-p7 (including) | 11.3-p7 (including) |
| Freebsd | Freebsd | 11.3-p8 (including) | 11.3-p8 (including) |
| Freebsd | Freebsd | 11.3-p9 (including) | 11.3-p9 (including) |
| 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 | 12.1 (including) | 12.1 (including) |
| Freebsd | Freebsd | 12.1-p1 (including) | 12.1-p1 (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 | 12.2 (including) | 12.2 (including) |
The use of previously-freed memory can have any number of adverse consequences, ranging from the corruption of valid data to the execution of arbitrary code, depending on the instantiation and timing of the flaw. The simplest way data corruption may occur involves the system’s reuse of the freed memory. Use-after-free errors have two common and sometimes overlapping causes:
In this scenario, the memory in question is allocated to another pointer validly at some point after it has been freed. The original pointer to the freed memory is used again and points to somewhere within the new allocation. As the data is changed, it corrupts the validly used memory; this induces undefined behavior in the process. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.