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-rw-r--r--pkg/sentry/usermem/usermem.go6
1 files changed, 5 insertions, 1 deletions
diff --git a/pkg/sentry/usermem/usermem.go b/pkg/sentry/usermem/usermem.go
index 1d6c0b4d6..75ac4d22d 100644
--- a/pkg/sentry/usermem/usermem.go
+++ b/pkg/sentry/usermem/usermem.go
@@ -181,7 +181,11 @@ func CopyObjectOut(ctx context.Context, uio IO, addr Addr, src interface{}, opts
Addr: addr,
Opts: opts,
}
- return w.Write(binary.Marshal(nil, ByteOrder, src))
+ // Allocate a byte slice the size of the object being marshaled. This
+ // adds an extra reflection call, but avoids needing to grow the slice
+ // during encoding, which can result in many heap-allocated slices.
+ b := make([]byte, 0, binary.Size(src))
+ return w.Write(binary.Marshal(b, ByteOrder, src))
}
// CopyObjectIn copies a fixed-size value or slice of fixed-size values from