From 3b2577ced39194fdd2f1359136c7e176d8de5576 Mon Sep 17 00:00:00 2001 From: Keith Randall Date: Sat, 20 Sep 2014 23:31:11 -0700 Subject: [PATCH] runtime: be very careful with bad pointer tests Saw this on a test: runtime: bad pointer in frame runtime_test.testSetPanicOnFault at 0xc20801c6b0: 0xfff fatal error: bad pointer! runtime stack: ... copystack(0xc2081bf7a0, 0x1000) /root/work/solaris-amd64-smartos-2dde8b453d26/go/src/runtime/stack.c:621 +0x173 fp=0xfffffd7ffd5ffee0 sp=0xfffffd7ffd5ffe20 runtime.newstack() /root/work/solaris-amd64-smartos-2dde8b453d26/go/src/runtime/stack.c:774 +0x552 fp=0xfffffd7ffd5fff90 sp=0xfffffd7ffd5ffee0 runtime.morestack() /root/work/solaris-amd64-smartos-2dde8b453d26/go/src/runtime/asm_amd64.s:324 +0x90 fp=0xfffffd7ffd5fff98 sp=0xfffffd7ffd5fff90 goroutine 163354 [stack growth]: ... runtime.convT2E(0x587000, 0xc20807bea8, 0x0, 0x0) /root/work/solaris-amd64-smartos-2dde8b453d26/go/src/runtime/iface.go:141 +0xd2 fp=0xc20801c678 sp=0xc20801c640 runtime_test.testSetPanicOnFault(0xc20822c510, 0xfff, 0xc20801c748) /root/work/solaris-amd64-smartos-2dde8b453d26/go/src/runtime/runtime_test.go:211 +0xc6 fp=0xc20801c718 sp=0xc20801c678 ... This test is testing bad pointers. It loads the bad pointer into a pointer variable, but before it gets a chance to dereference it, calls convT2E. That call causes a stack copy, which exposes that live but bad pointer variable. LGTM=dvyukov R=golang-codereviews, dvyukov CC=golang-codereviews https://golang.org/cl/146880043 --- src/runtime/runtime_test.go | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/src/runtime/runtime_test.go b/src/runtime/runtime_test.go index 3c4075842b..1688364a8e 100644 --- a/src/runtime/runtime_test.go +++ b/src/runtime/runtime_test.go @@ -206,9 +206,8 @@ func testSetPanicOnFault(t *testing.T, addr uintptr, nfault *int) { // addresses that have had C or kernel pages mapped there // readable by user code. So just log the content. // If no addresses fault, we'll fail the test. - var p *int - p = (*int)(unsafe.Pointer(addr)) - t.Logf("addr %#x: %#x\n", addr, *p) + v := *(*byte)(unsafe.Pointer(addr)) + t.Logf("addr %#x: %#x\n", addr, v) } func eqstring_generic(s1, s2 string) bool { -- 2.50.0