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43 lines
1.6 KiB
Diff
43 lines
1.6 KiB
Diff
From 2c5c1fd0d2a2a96fab750fa332cb703022c16c04 Mon Sep 17 00:00:00 2001
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From: John Dias <joaodias@google.com>
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Date: Wed, 9 Nov 2016 11:03:57 -0800
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Subject: [PATCH] perf: don't leave group_entry on sibling list
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(use-after-free)
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When perf_group_detach is called on a group leader,
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it should empty its sibling list. Otherwise, when
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a sibling is later deallocated, list_del_event()
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removes the sibling's group_entry from its current
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list, which can be the now-deallocated group leader's
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sibling list (use-after-free bug).
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Bug: 32402548
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Change-Id: I99f6bc97c8518df1cb0035814368012ba72ab1f1
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Signed-off-by: John Dias <joaodias@google.com>
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---
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kernel/events/core.c | 7 +++++++
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1 file changed, 7 insertions(+)
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diff --git a/kernel/events/core.c b/kernel/events/core.c
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index 01eab13ec0e7e..b7e1e224f07e9 100644
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--- a/kernel/events/core.c
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+++ b/kernel/events/core.c
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@@ -1449,10 +1449,17 @@ static void perf_group_detach(struct perf_event *event)
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* If this was a group event with sibling events then
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* upgrade the siblings to singleton events by adding them
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* to whatever list we are on.
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+ * If this isn't on a list, make sure we still remove the sibling's
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+ * group_entry from this sibling_list; otherwise, when that sibling
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+ * is later deallocated, it will try to remove itself from this
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+ * sibling_list, which may well have been deallocated already,
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+ * resulting in a use-after-free.
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*/
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list_for_each_entry_safe(sibling, tmp, &event->sibling_list, group_entry) {
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if (list)
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list_move_tail(&sibling->group_entry, list);
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+ else
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+ list_del_init(&sibling->group_entry);
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sibling->group_leader = sibling;
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/* Inherit group flags from the previous leader */
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