Re: [go-nuts] Need help: Calling panic() is corrupting system stack

[robert engels]

Unfortunately, I am on OSX - and Go doesn’t appear to generate a core dump on panic despite the GOTRACEBACK setting. That being said, the stack-traces look ok to me. See attached. -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/9E0182AE-9759-4371-8DE8-2B837438F9B9%40ix.netcom.com.

test.out.txt
Description: application/applefile

On Apr 3, 2023, at 11:59 PM, mariappan balraj <mariappan.bal...@gmail.com> wrote: Hi Robert, I have published the test case on github. Please find the links. Please let me know if you need any information. I am ready to provide and support. https://github.com/MariappanBalraj/test_cgo_panic https://github.com/MariappanBalraj/test_cgo_panic.git https://github.com/MariappanBalraj/test_cgo_panic/archive/refs/heads/main.zip Best Regards Mariappan On Mon, Apr 3, 2023 at 9:50 AM Robert Engels <reng...@ix.netcom.com> wrote: I would start by publishing a small reproducible test case on github that fully compiles that demonstrates the issue.   On Apr 2, 2023, at 10:59 PM, mariappan balraj <mariappan.bal...@gmail.com> wrote:  Hello Go Experts, It is good if someone can help on this? Best Regards Mariappan On Sat, Apr 1, 2023 at 7:45 AM mariappan balraj <mariappan.bal...@gmail.com> wrote: Hello Go experts, Could someone please help to resolve this issue? Best Regards Mariappan On Thu, Mar 30, 2023 at 2:52 PM mariappan balraj <mariappan.bal...@gmail.com> wrote: Hello Go Experts, When panic() is called from Go function, in the below call sequence, runtime.unwindm() [which is defer function of  runtime.cgocallbackg1] is called. This function is unwinding the system stack. Later, as part of the function addOneOpenDeferFrame(), systemstack() is called to run a function in the system stack. This will use the stack which is allocated for C function calls. This makes stack unwinding impossible in case of panic() is called. Can someone please help me to fix this issue? (dlv) bt  0  0x00000000004054e6 in runtime.unwindm     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go:326  1  0x0000000000405446 in runtime.cgocallbackg1.func3     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go:304  2  0x00000000004340c8 in runtime.deferCallSave     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/panic.go:796  3  0x0000000000433fa5 in runtime.runOpenDeferFrame     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/panic.go:769  4  0x0000000000434332 in runtime.gopanic     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/panic.go:884  5  0x00000000004642a7 in main.Test4     at ./export.go:7     at ./export.go:7  6  0x000000000046431c in _cgoexp_78b81bbf688e_Test4     at _cgo_gotypes.go:61  7  0x000000000040535b in runtime.cgocallbackg1     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go:315  8  0x0000000000405079 in runtime.cgocallbackg     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go:234  9  0x0000000000461b0f in runtime.cgocallbackg     at <autogenerated>:1 10  0x000000000045f3f4 in runtime.cgocallback     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s:998 11  0x00000000004641bd in crosscall2     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgo/asm_amd64.s:30 12  0x0000000000464386 in C.Test4     at /tmp/go-build/_cgo_export.c:33 13  0x0000000000464432 in C.test1     at ./hello.go:9 14  0x000000000046444d in C.test2     at ./hello.go:14 15  0x0000000000464468 in C.test3 15  0x0000000000464468 in C.test3     at ./hello.go:19 16  0x00000000004644a7 in C._cgo_78b81bbf688e_Cfunc_test3     at /tmp/go-build/cgo-gcc-prolog:49 17  0x000000000045f2e4 in runtime.asmcgocall     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s:848 18  0x000000000046448a in C._cgo_78b81bbf688e_Cfunc_test3     at /tmp/go-build/cgo-gcc-prolog:44 19  0x0000000000404f0a in runtime.cgocall     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go:167 20  0x0000000000464245 in main._Cfunc_test3     at _cgo_gotypes.go:39 21  0x00000000004642d7 in main.main     at ./hello.go:33 22  0x0000000000437073 in runtime.main     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/proc.go:250 23  0x000000000045f5e1 in runtime.goexit     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s:1598 254 func cgocallbackg1(fn, frame unsafe.Pointer, ctxt uintptr) { 304         defer unwindm(&restore) 326 func unwindm(restore *bool) { 327         if *restore { 328                 // Restore sp saved by cgocallback during 329                 // unwind of g's stack (see comment at top of file). 330                 mp := acquirem() 331                 sched := &mp.g0.sched 332                 sched.sp = *(*uintptr)(unsafe.Pointer(sched.sp + alignUp(sys.MinFrameSize, sys.StackAlign))) (dlv) > runtime.addOneOpenDeferFrame() /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/panic.go:642 (PC: 0x433a45) Warning: debugging optimized function    637: func addOneOpenDeferFrame(gp *g, pc uintptr, sp unsafe.Pointer) {    638:         var prevDefer *_defer    639:         if sp == nil {    640:                 prevDefer = gp._defer    641:                 pc = prevDefer.framepc => 642:                 sp = unsafe.Pointer(prevDefer.sp)    643:         }    644:         systemstack(func() {    645:                 gentraceback(pc, uintptr(sp), 0, gp, 0, nil, 0x7fffffff,    646:                         func(frame *stkframe, unused unsafe.Pointer) bool {    647:                                 if prevDefer != nil && prevDefer.sp == frame.sp { (dlv) bt  0  0x0000000000433a45 in runtime.addOneOpenDeferFrame     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/panic.go:642  1  0x0000000000434357 in runtime.gopanic     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/panic.go:886  2  0x00000000004642a7 in main.Test4     at ./export.go:7 On Tue, Mar 28, 2023 at 4:14 PM mariappan balraj <mariappan.bal...@gmail.com> wrote: Hello Go Experts, I am observing system stack corruption when panic() is called from go function. When panic is called from Test4(), as part of runtime.systemstack_switch(), the RSP and RBP is set in such a way that it will corrupt the stack.  Rbp = 0x00007ffdb188bd20===> This should be less than 0x7ffdb188bc50. But it is set to the value which is already used for CGO calls. So it is making the system stack to corrupt. When the core file is generated, it makes it unable to debug from the core file using dlv. Can someone please help on this issue? RBP 0x7ffdb188bc50 RA 0x45f3f4 runtime.cgocallback /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s 1003 RBP 0x7ffdb188bca0 RA 0x4641bd crosscall2 /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgo/asm_amd64.s 32 RBP 0x7ffdb188bcd0 RA 0x464386 C.Test4 /tmp/go-build/_cgo_export.c 35 RBP 0x7ffdb188bce0 RA 0x464432 C.test1 /home/soomohan/mbalraj/test/hello.go 10 RBP 0x7ffdb188bd00 RA 0x46444d C.test2 /home/soomohan/mbalraj/test/hello.go 15 RBP 0x7ffdb188bd20 RA 0x464468 C.test3 /home/soomohan/mbalraj/test/hello.go 20 RBP 0x7ffdb188bd50 RA 0x4644a7 C._cgo_78b81bbf688e_Cfunc_test3 /tmp/go-build/cgo-gcc-prolog 51 go version go version go1.20.2 linux/amd64 //hello.go package main /* #include <stdio.h> extern void Test4(void); void test1(void) {    Test4(); } void test2(void) {     int val = 2;     test1(); } void test3(void) {     int val = 3;     test2(); } void test4(void) {     printf("Test4()"); } */ import "C" func Test5() {     C.test4() } func main() {     C.test3() } //export.go package main import "C" //export Test4 func Test4() {     panic("Panic inside Test4")     //Test5() } I have written the following script test.start to debug this issue further in DLV. def command_goroutine_start_line(args):     regs = registers().Regs     rip = 0     for reg in regs:         if reg.Name == "Rbp":             rbp = int(reg.Value, 16)         elif reg.Name == "Rip":             rip = int(reg.Value, 16)     da = disassemble(StartPC=rip, EndPC=rip+1).Disassemble     print("RBP 0x%x RIP 0x%x %s %s %s" % (rbp, rip, da[0].Loc.Function.Name_, da[0].Loc.File, da[0].Loc.Line))         while True:         mem = examine_memory(rbp, 8).Mem         val = 0         for i in range(len(mem)):             val <<= 8             val += mem[len(mem) - i - 1]         prbp = val         mem = examine_memory(rbp + 8, 8).Mem         val = 0         for i in range(len(mem)):             val <<= 8             val += mem[len(mem) - i - 1]         ra = val         da = disassemble(StartPC=ra, EndPC=ra+1).Disassemble         print("RBP 0x%x RA 0x%x %s %s %s" % (prbp, ra, da[0].Loc.Function.Name_, da[0].Loc.File, da[0].Loc.Line))         if prbp == 0:            break         rbp = prbp def main():         dlv_command("config alias goroutine_start_line gsl") (dlv)bt RBP 0x0 RA 0x45f5e1 runtime.goexit /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s 1599  0  0x0000000000433b04 in runtime.addOneOpenDeferFrame.func1     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/panic.go:646  1  0x000000000045f0c0 in runtime.systemstack_switch     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s:463  2  0x0000000000433a89 in runtime.addOneOpenDeferFrame     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/panic.go:644  3  0x0000000000434357 in runtime.gopanic     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/panic.go:886  4  0x00000000004642a7 in main.Test4     at ./export.go:7  5  0x000000000046431c in _cgoexp_78b81bbf688e_Test4     at _cgo_gotypes.go:61  6  0x000000000040535b in runtime.cgocallbackg1     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go:315  7  0x0000000000405079 in runtime.cgocallbackg     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go:234  8  0x0000000000461b0f in runtime.cgocallbackg     at <autogenerated>:1  9  0x000000000045f3f4 in runtime.cgocallback     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s:998 10  0x0000000000000001 in ???     at ?:-1 11  0x0000000000464386 in C.Test4     at /tmp/go-build/_cgo_export.c:33 12  0x0000000000464432 in C.test1     at ./hello.go:9 13  0x000000000046444d in C.test2     at ./hello.go:14 14  0x0000000000464468 in C.test3     at ./hello.go:19 15  0x00000000004644a7 in C._cgo_78b81bbf688e_Cfunc_test3 15  0x00000000004644a7 in C._cgo_78b81bbf688e_Cfunc_test3     at /tmp/go-build/cgo-gcc-prolog:49 16  0x000000000045f2e4 in runtime.asmcgocall     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s:848 17  0x000000000046448a in C._cgo_78b81bbf688e_Cfunc_test3     at /tmp/go-build/cgo-gcc-prolog:44 18  0x0000000000404f0a in runtime.cgocall     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go:167 19  0x0000000000464245 in main._Cfunc_test3     at _cgo_gotypes.go:39 20  0x00000000004642d7 in main.main     at ./hello.go:33 21  0x0000000000437073 in runtime.main     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/proc.go:250 22  0x000000000045f5e1 in runtime.goexit     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s:1598 (dlv)source test.star (dlv)gsl (dlv) gsl RBP 0xc000048c68 RIP 0x433b04 runtime.addOneOpenDeferFrame.func1 /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/panic.go 646 RBP 0xc000048d28 RA 0x434357 runtime.gopanic /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/panic.go 905 RBP 0xc000048d48 RA 0x4642a7 main.Test4 /home/soomohan/mbalraj/test/export.go 7 RBP 0xc000048d58 RA 0x46431c _cgoexp_78b81bbf688e_Test4 _cgo_gotypes.go 62 RBP 0xc000048e18 RA 0x40535b runtime.cgocallbackg1 /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go 323 RBP 0xc000048ea8 RA 0x405079 runtime.cgocallbackg /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go 240 RBP 0xc000048ed0 RA 0x461b0f runtime.cgocallbackg <autogenerated> 1 RBP 0x7ffdb188bc50 RA 0x45f3f4 runtime.cgocallback /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s 1003 RBP 0x7ffdb188bca0 RA 0x4641bd crosscall2 /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgo/asm_amd64.s 32 RBP 0x7ffdb188bcd0 RA 0x464386 C.Test4 /tmp/go-build/_cgo_export.c 35 RBP 0x7ffdb188bce0 RA 0x464432 C.test1 /home/soomohan/mbalraj/test/hello.go 10 RBP 0x7ffdb188bd00 RA 0x46444d C.test2 /home/soomohan/mbalraj/test/hello.go 15 RBP 0x7ffdb188bd20 RA 0x464468 C.test3 /home/soomohan/mbalraj/test/hello.go 20 RBP 0x7ffdb188bd50 RA 0x4644a7 C._cgo_78b81bbf688e_Cfunc_test3 /tmp/go-build/cgo-gcc-prolog 51 RBP 0xc000048f38 RA 0x45f2e4 runtime.asmcgocall /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s 852 RBP 0xc000048f60 RA 0x464245 main._Cfunc_test3 _cgo_gotypes.go 40 RBP 0xc000048f70 RA 0x4642d7 main.main /home/soomohan/mbalraj/test/hello.go 33 RBP 0xc000048fd0 RA 0x437073 runtime.main /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/proc.go 260 RBP 0x0 RA 0x45f5e1 runtime.goexit /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s 1599 (dlv)si (dlv)bt  0  0x000000000045587f in runtime.gentraceback     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/traceback.go:32  1  0x000000000045f0c0 in runtime.systemstack_switch     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s:463  2  0x0000000000433a89 in runtime.addOneOpenDeferFrame     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/panic.go:644  3  0x0000000000434357 in runtime.gopanic     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/panic.go:886  4  0x00000000004642a7 in main.Test4     at ./export.go:7  5  0x000000000046431c in _cgoexp_78b81bbf688e_Test4     at _cgo_gotypes.go:61  6  0x000000000040535b in runtime.cgocallbackg1     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go:315  7  0x0000000000405079 in runtime.cgocallbackg     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go:234  8  0x0000000000461b0f in runtime.cgocallbackg     at <autogenerated>:1  9  0x000000000045f3f4 in runtime.cgocallback     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s:998 10  0x0000000000000001 in ???     at ?:-1 11  0x0000000000464386 in C.Test4     at /tmp/go-build/_cgo_export.c:33 12  0x0000000000464432 in C.test1     at ./hello.go:9 13  0x000000000046444d in C.test2     at ./hello.go:14 14  0x0000000000464468 in C.test3     at ./hello.go:19 15  0x0000000000433b4b in runtime.addOneOpenDeferFrame.func1 15  0x0000000000433b4b in runtime.addOneOpenDeferFrame.func1     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/panic.go:645 16  0x000000000045f129 in runtime.systemstack     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s:496 17  0x0000000000461da5 in runtime.newproc     at <autogenerated>:1 18  0x00000000004cc720 in ???     at ?:-1 19  0x000000000046431c in _cgoexp_78b81bbf688e_Test4     at _cgo_gotypes.go:61 20  0x000000000040535b in runtime.cgocallbackg1     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go:315 21  0x0000000000405079 in runtime.cgocallbackg     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go:234 22  0x0000000000461b0f in runtime.cgocallbackg     at <autogenerated>:1 23  0x000000000045f3f4 in runtime.cgocallback     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s:998 24  0x000000000045f0c0 in runtime.systemstack_switch     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s:463 25  0x0000000000404f0a in runtime.cgocall     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go:167 26  0x0000000000464245 in main._Cfunc_test3     at _cgo_gotypes.go:39 27  0x00000000004642d7 in main.main     at ./hello.go:33 28  0x0000000000437073 in runtime.main     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/proc.go:250 29  0x000000000045f5e1 in runtime.goexit     at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s:1598 (dlv) regs  (dlv) regs     Rip = 0x000000000045587f     Rsp = 0x00007ffdb188ba08     Rax = 0x000000000040535b     Rbx = 0x000000c000048d68     Rcx = 0x0000000000000000     Rdx = 0x0000000000433b60     Rsi = 0x0000000000000000     Rdi = 0x000000c0000061a0     Rbp = 0x00007ffdb188bd20      R8 = 0x0000000000000000      R9 = 0x000000007fffffff     R10 = 0x00007ffdb188bd80     R11 = 0x0000000000000000     R12 = 0x00007ffdb188ba88     R13 = 0x000000c000048c18     R14 = 0x00000000004cc720     R15 = 0x0000000000000000  Rflags = 0x0000000000000246    [PF ZF IF IOPL=0]      Es = 0x0000000000000000      Cs = 0x0000000000000033      Ss = 0x000000000000002b      Ds = 0x0000000000000000      Fs = 0x0000000000000000      Gs = 0x0000000000000000 Fs_base = 0x000015128ba66740 Gs_base = 0x0000000000000000 Best Regards Mariappan -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/CAKKWi6TOAChrRs64UBrNJSPFdFkYHhWiHPsDzu%2BMKPck9BOhVQ%40mail.gmail.com. -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/CAKKWi6RibSTdJW_Uc5Va31cj4gB9MiBrze%2BZifWYVis83h6Mnw%40mail.gmail.com. -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/9E0182AE-9759-4371-8DE8-2B837438F9B9%40ix.netcom.com.