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From: Peter Zijlstra <peterz@infradead.org>
To: linux-kernel@vger.kernel.org, mingo@kernel.org
Cc: tglx@linutronix.de, dan.j.williams@intel.com,
	torvalds@linux-foundation.org,
	Dan Carpenter <dan.carpenter@oracle.com>,
	"Peter Zijlstra" <peterz@infradead.org>
Subject: [PATCH 1/7] perf: Fix possible Spectre-v1 for aux_pages
Date: Fri, 20 Apr 2018 15:14:08 +0200
Message-ID: <20180420131631.720909184@infradead.org> (raw)
In-Reply-To: <20180420131407.721875616@infradead.org>

[-- Attachment #0: peterz-spectre1-1.patch --]
[-- Type: text/plain, Size: 899 bytes --]

> kernel/events/ring_buffer.c:871 perf_mmap_to_page() warn: potential spectre issue 'rb->aux_pages'

Userspace controls @pgoff through the fault address. Sanitize the
array index before doing the array dereference.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
---
 kernel/events/ring_buffer.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/kernel/events/ring_buffer.c
+++ b/kernel/events/ring_buffer.c
@@ -867,8 +867,10 @@ perf_mmap_to_page(struct ring_buffer *rb
 			return NULL;
 
 		/* AUX space */
-		if (pgoff >= rb->aux_pgoff)
-			return virt_to_page(rb->aux_pages[pgoff - rb->aux_pgoff]);
+		if (pgoff >= rb->aux_pgoff) {
+			int aux_pgoff = array_index_nospec(pgoff - rb->aux_pgoff, rb->aux_nr_pages);
+			return virt_to_page(rb->aux_pages[aux_pgoff]);
+		}
 	}
 
 	return __perf_mmap_to_page(rb, pgoff);

  reply index

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-20 13:14 [PATCH 0/7] Various Spectre-v1 fixes Peter Zijlstra
2018-04-20 13:14 ` Peter Zijlstra [this message]
2018-04-20 13:14 ` [PATCH 2/7] perf,x86: Fix possible Spectre-v1 for hw_perf_event Peter Zijlstra
2018-04-20 13:14 ` [PATCH 3/7] perf,x86: Fix possible Spectre-v1 for x86_pmu::event_map() Peter Zijlstra
2018-04-20 13:14 ` [PATCH 4/7] perf,x86/msr: Fix possible Spectre-v1 for msr Peter Zijlstra
2018-04-20 13:14 ` [PATCH 5/7] perf,x86/cstate: Fix possible Spectre-v1 for pkg_msr Peter Zijlstra
2018-04-20 13:14 ` [PATCH 6/7] sched: Fix possible Spectre-v1 for sched_prio_to_weight[] Peter Zijlstra
2018-04-20 13:14 ` [PATCH 7/7] sched,autogroup: Fix possible Spectre-v1 for sched_prio_to_weight Peter Zijlstra
2018-04-23  1:03 ` [PATCH 0/7] Various Spectre-v1 fixes Michal Hocko
2018-04-23  9:33   ` Peter Zijlstra
2018-04-23 13:50     ` Dan Williams
2018-04-23 16:47     ` Michal Hocko

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