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.
This patch adds address validation for the user supplied kernel filters.
Cc: sta...@vger.kernel.org # v4.7
Reported-by: Adrian Hunter <adrian.hun...@intel.com>
Signed-off-by: Alexander Shishkin <alexander.shish...@linux.intel.com>
---
arch/x86/events/intel/pt.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c
index 5ec0100e3f..1f94963a28 100644
--- a/arch/x86/events/intel/pt.c
+++ b/arch/x86/events/intel/pt.c
@@ -1074,6 +1074,11 @@ static void pt_addr_filters_fini(struct perf_event
*event)
event->hw.addr_filters = NULL;
}
+static inline bool valid_kernel_ip(unsigned long ip)
+{
+ return virt_addr_valid(ip) && kernel_ip(ip);
+}
+
static int pt_event_addr_filters_validate(struct list_head *filters)
{
struct perf_addr_filter *filter;
@@ -1084,7 +1089,7 @@ static int pt_event_addr_filters_validate(struct
list_head *filters)
if (!filter->range || !filter->size)
return -EOPNOTSUPP;
- if (!filter->inode && !kernel_ip(filter->offset))
+ if (!filter->inode && !valid_kernel_ip(filter->offset))
return -EINVAL;
if (++range > pt_cap_get(PT_CAP_num_address_ranges))
--
2.9.3
