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
}
--
2.9.3
