CVE-2022-48874

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

misc: fastrpc: Fix use-after-free and race in fastrpc_map_find

Currently, there is a race window between the point when the mutex is unlocked in fastrpc_map_lookup and the reference count increasing (fastrpc_map_get) in fastrpc_map_find, which can also lead to use-after-free.

So lets merge fastrpc_map_find into fastrpc_map_lookup which allows us to both protect the maps list by also taking the &fl->lock spinlock and the reference count, since the spinlock will be released only after. Add take_ref argument to make this suitable for all callers.

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/9446fa1683a7e3937d9970248ced427c1983a1c5
• https://git.kernel.org/stable/c/a50c5c25b6e7d2824698c0e6385f882a18f4a498