On 8/13/22, Demi Marie Obenour wrote:
On 8/13/22, Kevin Kofler via devel wrote:martin luther wrote:should we implement https://github.com/GrapheneOS/hardened_malloc/ it is hardened memory allocate it will increase the security of fedora according to the graphene os team it can be ported to linux as well need to look at itCCing Daniel Micay who wrote hardened_malloc.There are several questions that come up: [[snip]]
It seems to me that hardened_malloc could increase working set and RAM desired by something like 10% compared to glibc for some important workloads, such as Fedora re-builds. From page 22 of [1] (attached here; 203KB), the graph of number of requests versus requested size shows that blocks of size <= 128 were requested tens to thousands of times more often than all the rest. For sizes from 0 through 128, the "Size classes" section of README.md of [2] documents worst-case internal fragmentation (in "slabs") of 93.75% to 11.72%. That seems too high. Where are actual measurements for workloads such as Fedora re-builds? (Also note that the important special case of malloc(0), which is analogous to (gensym) of Lisp and is implemented internally as malloc(1), consumes 16 bytes and has a fragmentation of 93.75% for both glibc and hardened_malloc. The worst fragmentation happens for *every* call to malloc(0), which occurred about 800,000 times in the sample. Yikes!) [1] https://blog.linuxplumbersconf.org/2016/ocw/system/presentations/3921/original/LPC%202016%20-%20linux%20and%20glibc_%20The%204.5TiB%20malloc%20API%20trace.pdf [2] https://github.com/GrapheneOS/hardened_malloc/
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