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Date: Tue, 28 May 2024 11:16:08 +0900
To: cygwin@cygwin.com
Cc: Jeremy Drake <cygwin@jdrake.com>
Subject: Re: frequent hangs running ldd
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From: Takashi Yano via Cygwin <cygwin@cygwin.com>
Reply-To: Takashi Yano <takashi.yano@nifty.ne.jp>
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Hi Jeremy,

On Tue, 28 May 2024 10:58:00 +0900
Takashi Yano wrote:
> On Fri, 24 May 2024 19:29:43 -0700 (PDT)
> Jeremy Drake wrote:
> > On Fri, 24 May 2024, Jeremy Drake wrote:
> > 
> > > On Fri, 24 May 2024, Jeremy Drake wrote:
> > >
> > > > Looking at !address, it seems Windows put the PEB, TEBs, and stacks in the
> > > > area where the cygheap should be.  Way to go, ASLR :P
> > >
> > > I think the fix for this would be to add -Wl,--disable-high-entropy-va to
> > > ldh_LDFLAGS, as was done for strace and cygcheck at least.  I used peflags
> > > -d0 /usr/bin/ldh.exe and I'm not seeing a hang after that.
> > 
> > Sorry, that was peflags -e0 not -d0 (dynamicbase is still on):
> > $ peflags -v /usr/bin/ldh.exe
> > /usr/bin/ldh.exe:
> > coff(0x0226[+executable_image,+line_nums_stripped,+bigaddr,+sepdbg])
> > pe(0x0140[+dynamicbase,+nxcompat])
> 
> You are right!
> 
> It seems that VirtualAlloc() in cygheap_init() in mm/cygheap.cc
> fails when the address range which cygwin uses is occupied due to
> high-entropy-va in ldh.exe.
> 
> Thanks for the analysis.

Would you make a patch for that?

-- 
Takashi Yano <takashi.yano@nifty.ne.jp>

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