Currently, for data moving, we generate an msanread of the source,
followed by an msanwrite of the destination. msanread checks
the source is initialized.
This has a problem: if the source is an aggregate type containing
alignment paddings, the padding bytes may not be thought as
initialized by MSAN. If we copy the aggregate type by value, if
it counts as a read, MSAN reports using uninitialized data. This
CL changes it to use __msan_memmove for data copying, which tells
MSAN to propagate initialized-ness but not check for it.
Caveat: technically __msan_memmove is not a public API of MSAN,
although the C compiler does generate direct calls to it.
Also, when instrumenting a load of a struct, split the
instrumentation to fields, instead of generating an msanread for
the whole struct. This skips padding bytes, which may not be
considered initialized in MSAN.
Fixes#42820.
Change-Id: Id861c8bbfd94cfcccefcc58eaf9e4eb43b4d85c6
Reviewed-on: https://go-review.googlesource.com/c/go/+/270859
Trust: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
If we run 'go test ./...' in the misc module, we don't want to see
errors for these standalone files.
We could instead add +ignore tags to each file individually, but this
is exactly what a testdata directory is for.
Updates #30228
Change-Id: I7047ad888dd6aff701f5982d58b6a79f6a487c58
Reviewed-on: https://go-review.googlesource.com/c/163417
Run-TryBot: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Jay Conrod <jayconrod@google.com>
