Messages in this thread | | | From | pageexec@freemail ... | Date | Mon, 06 Jun 2011 17:58:16 +0200 | Subject | Re: [PATCH v5 8/9] x86-64: Emulate legacy vsyscalls |
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On 6 Jun 2011 at 17:33, Ingo Molnar wrote:
> Is it this commit: > > 320b2b8de126: mm: keep a guard page below a grow-down stack segment
yes and all the related ones.
> But you say that there's a Sun JVM breakage still left, right? Is > there a bugzilla # or simple .c reproducer for that?
i don't know if only that JVM is affected, the fact is that breaking the maps API breaks everyone who relied on it the same way.
also it's not fixable without reverting the *entire* approach. see, it's very simple: if the kernel lies about the stack boundary, it breaks the JVM and similar approaches, if it doesn't lie about it then it breaks other apps as you already found out.
as for bz/reproduction, neither exists, i read the JVM code carefully at the time (had actually remembered from other times) and just went ahead and fixed it properly in PaX.
for reproduction you'd have to trigger a stack overflow (not to be confused with a buffer overflow) on the main jvm thread, iirc, i have no idea how to pull that off. but you can easily write a small test app based on what i explained and test it but i hope it's obvious how the JVM logic breaks down with the maps changes.
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