perf/x86/intel/pt: Do validate the size of a kernel address filter

Right now, the kernel address filters in PT are prone to integer overflow
that may happen in adding filter's size to its offset to obtain the end
of the range. Such an overflow would also throw a #GP in the PT event
configuration path.

Fix this by explicitly validating the result of this calculation.

Reported-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: stable@vger.kernel.org # v4.7
Cc: stable@vger.kernel.org#v4.7
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160915151352.21306-4-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 7 insertions, 2 deletions

diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c
index 1f94963a283b..861a7d9cb60f 100644
--- a/arch/x86/events/intel/pt.c
+++ b/arch/x86/events/intel/pt.c
@@ -1089,8 +1089,13 @@ static int pt_event_addr_filters_validate(struct list_head *filters)
                 if (!filter->range || !filter->size)
                         return -EOPNOTSUPP;
 
-                if (!filter->inode && !valid_kernel_ip(filter->offset))
-                        return -EINVAL;
+                if (!filter->inode) {
+                        if (!valid_kernel_ip(filter->offset))
+                                return -EINVAL;
+
+                        if (!valid_kernel_ip(filter->offset + filter->size))
+                                return -EINVAL;
+                }
 
                 if (++range > pt_cap_get(PT_CAP_num_address_ranges))
                         return -EOPNOTSUPP;