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cmd/compile: add -d=checkptr to validate unsafe.Pointer rules

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This CL adds -d=checkptr as a compile-time option for adding
instrumentation to check that Go code is following unsafe.Pointer
safety rules dynamically. In particular, it currently checks two
things:

1. When converting unsafe.Pointer to *T, make sure the resulting
pointer is aligned appropriately for T.

2. When performing pointer arithmetic, if the result points to a Go
heap object, make sure we can find an unsafe.Pointer-typed operand
that pointed into the same object.

These checks are currently disabled for the runtime, and can also be
disabled through a new //go:nocheckptr annotation. The latter is
necessary for functions like strings.noescape, which intentionally
violate safety rules to workaround escape analysis limitations.

Fixes #22218.

Change-Id: If5a51273881d93048f74bcff10a3275c9c91da6a
Reviewed-on: https://go-review.googlesource.com/c/go/+/162237
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Matthew Dempsky 2019-02-12 19:40:42 -08:00
parent 3b003c3edb
commit 80a6fedea0
9 changed files with 159 additions and 1 deletions
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6
src/cmd/compile/internal/gc/inl.go
View file

@ -135,6 +135,12 @@ func caninl(fn *Node) {
return
}
// If marked "go:nocheckptr" and -d checkptr compilation, don't inline.
if Debug_checkptr != 0 && fn.Func.Pragma&NoCheckPtr != 0 {
reason = "marked go:nocheckptr"
return
}
// If marked "go:cgo_unsafe_args", don't inline, since the
// function makes assumptions about its argument frame layout.
if fn.Func.Pragma&CgoUnsafeArgs != 0 {