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SubjectRe: Linux 2.2.0pre2
In article <>, (Linus Torvalds) writes:
> - fix for an attack where you could cause a complete and utter lockup of
> the kernel as a normal user. Thanks to Michael Chastain for keeping the
> faith on this one and reminding me to fix it.

This is harmless compared to the attacks possible with /proc/<pid>/mem @)
All functions in fs/proc/mem.c are super-racy (the process/mm structure may
go away while it sleeps) and have other problems. Also they are completely
unreliable to use because they don't fault in pages. Alan's acX patches
have a patch that fix most races, except a few problems in the mem_mmap()
range checking. Fixing mmap completely is hard because doing it full may
lead to shared anonymous mappings.

These problems are in 2.0 too.

> If you haven't had problems with pre1, there should be no major cause to
> look at pre2. But if you haven't even looked at pre1 yet, please consider
> looking at the pre-2.2.0 kernels before it's too late. I'm going to be
> extremely rude to people who knew better but didn't test out the pre-
> kernels and then send me bug-reports on the released 2.2.0.

Out of memory handling seems to be poor in 2.2.0pre1. It gets into a strange
swap storm that does not do full HD bandwidth swapping, but small bursts of
IO with pauses.


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