Re: proxy-defpager for all users?

[Samuel Thibault]

Richard Braun, le mar. 06 nov. 2018 11:52:45 +0100, a ecrit:
> On Mon, Nov 05, 2018 at 11:02:47PM +0100, Samuel Thibault wrote:
> > proxy-defpager is typically set on /servers/default-pager, but its
> > permissions are by default 644, which makes it unusable by normal users,
> > it'd need to be 755 (see the x check in the defpager source).
> > 
> > Apart from allowing users to eat memory, which they currently already
> > can do anyway, is there any downside to making this 755 so people can
> > mount their own tmpfs?
> 
> I personally wondered why it wasn't the case from the start.
> 
> That being said, I'll use this as an opportunity to restate a core
> problem of Mach memory management, as I couldn't find it on the wiki.
> This problem may or may not be even more triggered by using unprivileged
> tmpfs instances.

I actually encountered such an issue with php7.3's shm testing, which
triggers an ext2fs crash due to a tmpfs issue. I'll probably add the
attached patch to the debian package for now, but it seems that the
server side of RPCs needs to be more careful about receiving data when
it's passed out of line.

Samuel

io-write-crash.patch
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