From 3b3f02627870a06de4e1fc3178d5bd23f627a97a Mon Sep 17 00:00:00 2001
From: Jamie Liu <jamieliu@google.com>
Date: Tue, 18 Dec 2018 11:51:22 -0800
Subject: Truncate ar before calling mm.breakCopyOnWriteLocked().
... as required by the latter's precondition.
PiperOrigin-RevId: 226033824
Change-Id: I6bc46d0e100c61cc58cb5fc69e70c4ca905cd92d
---
pkg/sentry/mm/pma.go | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/pkg/sentry/mm/pma.go b/pkg/sentry/mm/pma.go
index 5690fe6b4..63c50f719 100644
--- a/pkg/sentry/mm/pma.go
+++ b/pkg/sentry/mm/pma.go
@@ -138,6 +138,10 @@ func (mm *MemoryManager) getPMAsLocked(ctx context.Context, vseg vmaIterator, ar
var cowerr error
if opts.breakCOW {
+ if pend.Start() < ar.End {
+ // Adjust ar to reflect missing pmas.
+ ar.End = pend.Start()
+ }
var invalidated bool
pend, invalidated, cowerr = mm.breakCopyOnWriteLocked(pstart, ar)
if pend.Start() <= ar.Start {
@@ -189,6 +193,10 @@ func (mm *MemoryManager) getVecPMAsLocked(ctx context.Context, ars usermem.AddrR
if !pstart.Ok() {
pstart = mm.findOrSeekPrevUpperBoundPMA(ar.Start, pend)
}
+ if pend.Start() < ar.End {
+ // Adjust ar to reflect missing pmas.
+ ar.End = pend.Start()
+ }
pend, _, cowerr = mm.breakCopyOnWriteLocked(pstart, ar)
}
--
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