CVE-2022-3910

Use After Free vulnerability in Linux Kernel allows Privilege Escalation. An improper Update of Reference Count in io_uring leads to Use-After-Free and Local Privilege Escalation. When io_msg_ring was invoked with a fixed file, it called io_fput_file() which improperly decreased its reference count (leading to Use-After-Free and Local Privilege Escalation). Fixed files are permanently registered to the ring, and should not be put separately.

We recommend upgrading past commit https://github.com/torvalds/linux/commit/fc7222c3a9f56271fba02aabbfbae999042f1679 https://github.com/torvalds/linux/commit/fc7222c3a9f56271fba02aabbfbae999042f1679

Weakness 

Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code.

Affected Software 

Extended Description 

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.

Potential Mitigations 

References  

• https://github.com/torvalds/linux/commit/fc7222c3a9f56271fba02aabbfbae999042f1679
• https://kernel.dance/#fc7222c3a9f56271fba02aabbfbae999042f1679
• https://github.com/torvalds/linux/commit/fc7222c3a9f56271fba02aabbfbae999042f1679
• https://kernel.dance/#fc7222c3a9f56271fba02aabbfbae999042f1679