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[Bug libc/9832] New: LD_POINTER_GUARD does not fully work
- From: "tromey at redhat dot com" <sourceware-bugzilla at sourceware dot org>
- To: glibc-bugs at sources dot redhat dot com
- Date: 9 Feb 2009 23:17:14 -0000
- Subject: [Bug libc/9832] New: LD_POINTER_GUARD does not fully work
- Reply-to: sourceware-bugzilla at sourceware dot org
gdb has some automatic support for nexting over longjmp.
It relies on the user setting LD_POINTER_GUARD=0 to avoid
pointer mangling.
This code does not work on glibc 2.8 (Fedora 9).
I believe the problem is that on x86 (and x86-64),
LD_POINTER_GUARD=0 still does a transformation.
>From libc/sysdeps/unix/sysv/linux/i386/sysdep.h:
# define PTR_MANGLE(reg) xorl %gs:POINTER_GUARD, reg; \
roll $9, reg
The rotate is done unconditionally.
(x86-64 is similar)
--
Summary: LD_POINTER_GUARD does not fully work
Product: glibc
Version: 2.8
Status: NEW
Severity: normal
Priority: P2
Component: libc
AssignedTo: drepper at redhat dot com
ReportedBy: tromey at redhat dot com
CC: glibc-bugs at sources dot redhat dot com
http://sourceware.org/bugzilla/show_bug.cgi?id=9832
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