In the Linux kernel, the following vulnerability has been resolved:
serial: 8250: omap: Dont skip resource freeing if pm_runtime_resume_and_get() failed
Returning an error code from .remove() makes the driver core emit the little helpful error message:
remove callback returned a non-zero value. This will be ignored.
and then remove the device anyhow. So all resources that were not freed are leaked in this case. Skipping serial8250_unregister_port() has the potential to keep enough of the UART around to trigger a use-after-free.
So replace the error return (and with it the little helpful error message) by a more useful error message and continue to cleanup.
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 |
|---|---|---|---|
| Linux_kernel | Linux | * | 5.4.268 (excluding) |
| Linux_kernel | Linux | 5.5.0 (including) | 5.10.209 (excluding) |
| Linux_kernel | Linux | 5.11.0 (including) | 5.15.148 (excluding) |
| Linux_kernel | Linux | 5.16 (including) | 6.1.75 (excluding) |
| Linux_kernel | Linux | 6.2.0 (including) | 6.6.14 (excluding) |
| Linux_kernel | Linux | 6.7.0 (including) | 6.7.2 (excluding) |
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.