lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Tue, 20 Sep 2016 18:00:37 -0700 From: Linus Torvalds <torvalds@...ux-foundation.org> To: Kees Cook <keescook@...omium.org> Cc: Josh Poimboeuf <jpoimboe@...hat.com>, Alexander Viro <viro@...iv.linux.org.uk>, LKML <linux-kernel@...r.kernel.org> Subject: Re: [INFO] ratio of const vs dynamic usercopy On Tue, Sep 20, 2016 at 5:31 PM, Kees Cook <keescook@...omium.org> wrote: > > trace-cmd seemed to break for me (lost one of the CPU buffers?), so I > just did this manually: > > # echo __skip_check_object_size > set_ftrace_filter > # echo __check_object_size >> set_ftrace_filter > # echo 1 > function_profile_enabled > ... build the kernel 5 times ... I suspect other loads will give possibly radically different numbers. I like the kernel build as a benchmark, but at the same time I have to admit that it's fairly specific. It tends to do mostly some fairly simple filesystem stuff. It would be interesting to see what the most common direct callchains for the object size check is, though. Maybe there's only one or two really common cases (the page cache copies for read/write? I dunno) Maybe if we special-case those, that cuts down on the dynamic cases a lot. And obviously the reason it would be good to make that size check as uncommon as possible is that obviously once it's not a very common case, that makes it much more valid to enable this all by default and/or make more expensive checks. Linus
Powered by blists - more mailing lists