CVE-2024-56762
Description
[REJECTED CVE] A use-after-free (UAF) vulnerability was identified in the Linux kernel’s io_uring subsystem, specifically in SQPOLL error handling. If io_uring_alloc_task_context() fails while io_sq_thread() runs and completes before the error handling executes, io_sq_thread_finish() may attempt to access an already freed task, leading to potential system instability. While the issue is mostly theoretical and requires fault injection to trigger, could lead to crashes or unpredictable behavior.
Statement
This CVE has been rejected upstream: https://lore.kernel.org/linux-cve-announce/2025010720-REJECTED-2931@gregkh/
IO uring support enabled only in latest versions of Red Hat Enterprise Linux. The bug could happen only if some complex conditions, so the security impact is Moderate: "if io_uring_alloc_task_context() fails and then io_sq_thread() manages to run and complete before the rest of error handling code, which means io_sq_thread_finish() is looking at already killed task."
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Memory
The use of previously freed memory may corrupt valid data, if the memory area in question has been allocated and used properly elsewhere.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If chunk consolidation occurs after the use of previously freed data, the process may crash when invalid data is used as chunk information.
Confidentiality
Technical Impact: Read Memory
Read operations on freed memory can sometimes leak sensitive information instead of causing a crash
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If malicious data is entered before chunk consolidation can take place, it may be possible to take advantage of a write-what-where primitive to execute arbitrary code. 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.
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