frequent hangs running ldd

Tue May 28 01:58:00 GMT 2024

On 2024年5月24日 19:29:43 -0700 (PDT)
Jeremy Drake wrote:
> On 2024年5月24日, Jeremy Drake wrote:
>> > On 2024年5月24日, 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.
-- 
Takashi Yano <takashi.yano@nifty.ne.jp>