CVE-2022-48790

In the Linux kernel, the following vulnerability has been resolved:

nvme: fix a possible use-after-free in controller reset during load

Unlike .queue_rq, in .submit_async_event drivers may not check the ctrl readiness for AER submission. This may lead to a use-after-free condition that was observed with nvme-tcp.

The race condition may happen in the following scenario:

1. driver executes its reset_ctrl_work
2. -> nvme_stop_ctrl - flushes ctrl async_event_work
3. ctrl sends AEN which is received by the host, which in turn schedules AEN handling
4. teardown admin queue (which releases the queue socket)
5. AEN processed, submits another AER, calling the driver to submit
6. driver attempts to send the cmd ==> use-after-free

In order to fix that, add ctrl state check to validate the ctrl is actually able to accept the AER submission.

This addresses the above race in controller resets because the driver during teardown should:

1. change ctrl state to RESETTING
2. flush async_event_work (as well as other async work elements)

So after 1,2, any other AER command will find the ctrl state to be RESETTING and bail out without submitting the AER.

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://git.kernel.org/stable/c/0ead57ceb21bbf15963b4874c2ac67143455382f
• https://git.kernel.org/stable/c/0fa0f99fc84e41057cbdd2efbfe91c6b2f47dd9d
• https://git.kernel.org/stable/c/70356b756a58704e5c8818cb09da5854af87e765
• https://git.kernel.org/stable/c/9e956a2596ae276124ef0d96829c013dd0faf861
• https://git.kernel.org/stable/c/a25e460fbb0340488d119fb2e28fe3f829b7417e
• https://git.kernel.org/stable/c/e043fb5a0336ee74614e26f0d9f36f1f5bb6d606
• https://git.kernel.org/stable/c/0ead57ceb21bbf15963b4874c2ac67143455382f
• https://git.kernel.org/stable/c/0fa0f99fc84e41057cbdd2efbfe91c6b2f47dd9d
• https://git.kernel.org/stable/c/70356b756a58704e5c8818cb09da5854af87e765
• https://git.kernel.org/stable/c/9e956a2596ae276124ef0d96829c013dd0faf861
• https://git.kernel.org/stable/c/a25e460fbb0340488d119fb2e28fe3f829b7417e
• https://git.kernel.org/stable/c/e043fb5a0336ee74614e26f0d9f36f1f5bb6d606