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Linux kernel heap feng shui in 2022 An article by

and

describing the kernel changes that affected exploitation techniques for slab-related vulnerabilities over the last few years. duasynt.com/blog/linux-ker

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I believe the "post 5.0" part should be "post 5.9". Using separate caches for accounting was removed in this patch:

github.com

mm: memcg/slab: use a single set of kmem_caches for all allocations · torvalds/linux@10befea

Instead of having two sets of kmem_caches: one for system-wide and non-accounted allocations and the second one shared by all accounted allocations, we can use just one. The idea is simple: space ...

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As an addition, using separate caches for accounting was introduced again in 5.14, as pointed out by

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linux kernel introduced kmalloc-cg-* in 5.14. allocations using GFP_KERNEL_ACCOUNT will go in there. no wonder i cant use msg_msg spray on 5.17 while on Ubuntu 21.10 (5.13) i still can use it. github.com/torvalds/linux

7:45 PM · Jun 8, 2022Twitter Web App

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flex

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i think the caches get merged if CONFIG_MEMCG isn’t enabled, if anyone is curious.

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ahh what I was referring to is general purpose allocations with GFP_KERNEL_ACCOUNT. that's true MEMCG would make accounted special-purpose caches non-mergeable regardless of the kern version. if it's disabled then there's no kmem accounting. I'll expand 👍

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