linux-kernel - [PATCH v1 3/3] perf/x86/intel/pt: Do validate the size of a kernel address filter

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Message-Id: <20160915151352.21306-4-alexander.shishkin@linux.intel.com>
Date:   Thu, 15 Sep 2016 18:13:52 +0300
From:   Alexander Shishkin <alexander.shishkin@...ux.intel.com>
To:     Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:     Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
        vince@...ter.net, eranian@...gle.com,
        Arnaldo Carvalho de Melo <acme@...radead.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        stable@...r.kernel.org#v4.7
Subject: [PATCH v1 3/3] 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.

Cc: stable@...r.kernel.org # v4.7
Reported-by: Adrian Hunter <adrian.hunter@...el.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
---
 arch/x86/events/intel/pt.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c
index 1f94963a28..861a7d9cb6 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;
-- 
2.9.3