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| author | Keith Randall <khr@google.com> | 2017-12-04 14:47:32 -0800 |
|---|---|---|
| committer | Keith Randall <khr@golang.org> | 2017-12-05 00:10:10 +0000 |
| commit | dd7cbf3a846c2cb125ac65173abaf6a8b9f903ff (patch) | |
| tree | 8f40c24b842c5fdfd8951f20f95b8cc29b226e30 /src | |
| parent | 2ff2eab0d240ec4ccfbc05f17afa8d99c6fbed61 (diff) | |
| download | go-dd7cbf3a846c2cb125ac65173abaf6a8b9f903ff.tar.xz | |
cmd/compile: fix map assignment with panicking right-hand side
Make sure that when we're assigning to a map, we evaluate the
right-hand side before we attempt to insert into the map.
We used to evaluate the left-hand side to a pointer-to-slot-in-bucket
(which as a side effect does len(m)++), then evaluate the right-hand side,
then do the assignment. That clearly isn't correct when the right-hand side
might panic.
Fixes #22881
Change-Id: I42a62870ff4bf480568c9bdbf0bb18958962bdf0
Reviewed-on: https://go-review.googlesource.com/81817
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Diffstat (limited to 'src')
| -rw-r--r-- | src/cmd/compile/internal/gc/order.go | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/src/cmd/compile/internal/gc/order.go b/src/cmd/compile/internal/gc/order.go index 517aa5a8bf..de89adf0e0 100644 --- a/src/cmd/compile/internal/gc/order.go +++ b/src/cmd/compile/internal/gc/order.go @@ -427,10 +427,10 @@ func ordercall(n *Node, order *Order) { // to make sure that all map assignments have the form m[k] = x. // (Note: orderexpr has already been called on n, so we know k is addressable.) // -// If n is the multiple assignment form ..., m[k], ... = ..., the rewrite is +// If n is the multiple assignment form ..., m[k], ... = ..., x, ..., the rewrite is // t1 = m // t2 = k -// ...., t3, ... = x +// ...., t3, ... = ..., x, ... // t1[t2] = t3 // // The temporaries t1, t2 are needed in case the ... being assigned @@ -444,6 +444,11 @@ func ordermapassign(n *Node, order *Order) { Fatalf("ordermapassign %v", n.Op) case OAS: + if n.Left.Op == OINDEXMAP { + // Make sure we evaluate the RHS before starting the map insert. + // We need to make sure the RHS won't panic. See issue 22881. + n.Right = ordercheapexpr(n.Right, order) + } order.out = append(order.out, n) case OAS2, OAS2DOTTYPE, OAS2MAPR, OAS2FUNC: |