Messages in this thread | | | Date | Fri, 26 Apr 2013 15:15:10 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH 6/6] x86: kaslr: report kernel offset on panic |
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On 04/26/2013 03:13 PM, Borislav Petkov wrote: > On Fri, Apr 26, 2013 at 12:03:25PM -0700, Kees Cook wrote: >> When the system panics, include the kernel offset in the report to assist >> in debugging. >> >> Signed-off-by: Kees Cook <keescook@chromium.org> >> --- >> arch/x86/kernel/setup.c | 24 ++++++++++++++++++++++++ >> 1 file changed, 24 insertions(+) >> >> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c >> index fae9134..95a33b1 100644 >> --- a/arch/x86/kernel/setup.c >> +++ b/arch/x86/kernel/setup.c >> @@ -830,6 +830,18 @@ static void __init trim_low_memory_range(void) >> } >> >> /* >> + * Dump out kernel offset information on panic. >> + */ >> +static int >> +dump_kernel_offset(struct notifier_block *self, unsigned long v, void *p) >> +{ >> + pr_emerg("Kernel Offset: 0x%lx\n", >> + (unsigned long)&_text - __START_KERNEL); > > So what's wrong with subtracting the offset from the function addresses > on the stack so that traces can show the addresses as they are in > vmlinux, completely agnostic of any randomization? >
That really makes it harder to figure out what the heck the register content may mean...
-hpa
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