On Thu, Sep 15, 2016 at 04:29:43PM +0300, Alexander Shishkin wrote: > The kernel_ip() filter is used mostly by the DS/LBR code to look at the > branch addresses, but Intel PT also uses it to validate the address > filter offsets for kernel addresses, for which it is not sufficient: > supplying something in bits 64:48 that's not a sign extension of the lower > address bits (like 0xf00d000000000000) throws a #GP. > > In the interest of improving everybody's kernel address checks, this > patch adds address validation to kernel_ip(). > > Cc: sta...@vger.kernel.org # 4.7 > Reported-by: Adrian Hunter <adrian.hun...@intel.com> > Signed-off-by: Alexander Shishkin <alexander.shish...@linux.intel.com> > --- > arch/x86/events/perf_event.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h > index 5874d8de1f..88fb389356 100644 > --- a/arch/x86/events/perf_event.h > +++ b/arch/x86/events/perf_event.h > @@ -783,7 +783,7 @@ static inline bool kernel_ip(unsigned long ip) > #ifdef CONFIG_X86_32 > return ip > PAGE_OFFSET; > #else > - return (long)ip < 0; > + return (long)ip < 0 && virt_addr_valid(ip); > #endif > }
I have a slight performance worry, this ends up being called a _lot_ on older machines that have to do the PEBS LBR-fixup.
