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>
Otherwise it is possible that msan will consider the C result to be
partially initialized, which may cause msan to think that the Go stack
is partially uninitialized. The compiler will never mark the stack as
initialized, so without this CL it is possible for stack addresses to
be passed to msanread, which will cause a false positive error from msan.
Fixes#26209
Change-Id: I43a502beefd626eb810ffd8753e269a55dff8248
Reviewed-on: https://go-review.googlesource.com/122196
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This makes it much easier to run individual failing subtests.
Use $(go env CC) instead of always defaulting to clang; this makes it
easier to test with other compilers.
Run C binaries to detect incompatible compiler/kernel pairings instead
of sniffing versions.
updates #21196
Change-Id: I0debb3cc4a4244df44b825157ffdc97b5c09338d
Reviewed-on: https://go-review.googlesource.com/52910
Run-TryBot: Bryan Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
