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Re: toolchain/51237: $TOOLDIR/bin/...-install crashes

The following reply was made to PR toolchain/51237; it has been noted by GNATS.

From: (Christos Zoulas)
Subject: Re: toolchain/51237: $TOOLDIR/bin/...-install crashes
Date: Mon, 13 Jun 2016 11:06:03 -0400

 On Jun 13,  1:15pm, ( wrote:
 -- Subject: toolchain/51237: $TOOLDIR/bin/...-install crashes
 | >Number:         51237
 | >Category:       toolchain
 | >Synopsis:       $TOOLDIR/bin/...-install crashes
 | >Confidential:   no
 | >Severity:       critical
 | >Priority:       high
 | >Responsible:    toolchain-manager
 | >State:          open
 | >Class:          sw-bug
 | >Submitter-Id:   net
 | >Arrival-Date:   Mon Jun 13 13:15:00 +0000 2016
 | >Originator:     Martin Husemann
 | >Release:        NetBSD 7.99.30
 | >Organization:
 | The NetBSD Foundation, Inc.
 | >Environment:
 | System: NetBSD 7.99.30 NetBSD 7.99.30 (MODULAR) #521: Wed Jun 8 18:15:20 CEST 2016 sparc64
 | Architecture: sparc64
 | Machine: sparc64
 | >Description:
 | When building natively on sparc64 with ASLR enabled, I get random crashes
 | from install:
 You should be able to isolate it by using the ASLR debug flags. Once you
 get a command line that occasionally crashes, you can set the pax aslr
 flags to "fixed":
 sysctl -w security.pax.aslr.flags=0x20
 Then try a loop like:
 set +e
 for i in f ff fff ffff fffff ffffff fffffff ffffffff
     sysctl -w security.pax.aslr.flags=0x$i
     echo $i
 After that once you find the value that crashes it you can determine
 which part of the ASLR is at fault by or-ing in the following flags to
 the flags sysctl to disable the particular ASLR feature:
 #define PAX_ASLR_STACK          0x01
 #define PAX_ASLR_STACK_GAP      0x02
 #define PAX_ASLR_MMAP           0x04
 #define PAX_ASLR_EXEC_OFFSET    0x08
 #define PAX_ASLR_RTLD_OFFSET    0x10
 For example:
 sysctl -w security.pax.aslr.flags=0x21
 Will keep the "fixed" random number, but not play with the stack.

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