Cherry Zhang af8f4062c2 runtime: scan gp._panic in stack scan ... In runtime.gopanic, the _panic object p is stack allocated and referenced from gp._panic. With stack objects, p on stack is dead at the point preprintpanics runs. gp._panic points to p, but stack scan doesn't look at gp. Heap scan of gp does look at gp._panic, but it stops and ignores the pointer as it points to the stack. So whatever p points to may be collected and clobbered. We need to scan gp._panic explicitly during stack scan. To test it reliably, we introduce a GODEBUG mode "clobberfree", which clobbers the memory content when the GC frees an object. Fixes #30150. Change-Id: I11128298f03a89f817faa221421a9d332b41dced Reviewed-on: https://go-review.googlesource.com/c/161778 Run-TryBot: Cherry Zhang <cherryyz@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Keith Randall <khr@golang.org> Reviewed-by: Austin Clements <austin@google.com>		2019-02-13 15:49:22 +00:00
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testprog	runtime: scan gp._panic in stack scan	2019-02-13 15:49:22 +00:00
testprogcgo	runtime: fix CGO traceback frame count	2018-12-10 23:09:58 +00:00
testprognet	runtime, syscall: reset signal handlers to default in child	2017-06-14 14:00:56 +00:00