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Linux Security Hardening Cache Randomization Was Inadvertently Using The Same Seed
Ahead of the upcoming Linux 6.15 kernel cycle a few early pull requests have already been sent in to Linus Torvalds in advance of the anticipated v6.14 release on Sunday
CONFIG_RANDOM_KMALLOC_CACHES creates multiple copies of slab caches and makes kmalloc randomly pick one based on the code address in order to help fend off memory vulnerability exploits. Gong Ruiqi of Huawei who worked out the solution to the issue explained:"That literally means all kmalloc invoked via kvmalloc would use the same seed for cache randomization (CONFIG_RANDOM_KMALLOC_CACHES), which makes this hardening non-functional. The root cause of this problem, IMHO, is that using RET_IP only cannot identify the actual allocation site in case of kmalloc being called inside non-inlined wrappers or helper functions.
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