CVE-2022-49685

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

iio: trigger: sysfs: fix use-after-free on remove

Ensure that the irq_work has completed before the trigger is freed.

================================================================== BUG: KASAN: use-after-free in irq_work_run_list Read of size 8 at addr 0000000064702248 by task python3/25

Call Trace: irq_work_run_list irq_work_tick update_process_times tick_sched_handle tick_sched_timer __hrtimer_run_queues hrtimer_interrupt

Allocated by task 25: kmem_cache_alloc_trace iio_sysfs_trig_add dev_attr_store sysfs_kf_write kernfs_fop_write_iter new_sync_write vfs_write ksys_write sys_write

Freed by task 25: kfree iio_sysfs_trig_remove dev_attr_store sysfs_kf_write kernfs_fop_write_iter new_sync_write vfs_write ksys_write sys_write

==================================================================

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/31ff3309b47d98313c61b8301bf595820cc3cc33
• https://git.kernel.org/stable/c/4687c3f955240ca2a576bdc3f742d4d915b6272d
• https://git.kernel.org/stable/c/4ef1e521be610b720daeb7cf899fedc7db0274c4
• https://git.kernel.org/stable/c/5e39397d60dacc7f5d81d442c1c958eaaaf31128
• https://git.kernel.org/stable/c/78601726d4a59a291acc5a52da1d3a0a6831e4e8
• https://git.kernel.org/stable/c/b07a30a774b3c3e584a68dc91779c68ea2da4813
• https://git.kernel.org/stable/c/d6111e7bdb8ec27eb43d01c4cd4ff1620a75f7f2
• https://git.kernel.org/stable/c/fd5d8fb298a2866c337da635c79d63c3afabcaf7