Whenever I see fast* I think someone took shortcuts to make something “faster” without fully implementing the spec (or external constraints, like safe data access)
> On May 2, 2019, at 7:16 PM, Burak Serdar <bser...@ieee.org> wrote: > >> On Thu, May 2, 2019 at 6:02 PM XXX ZZZ <emartinez1...@gmail.com> wrote: >> >> No use of C via CGO at all. >> >> Afaik, there isn't any unsafe use of the string, we are basically reading it >> from a get parameter (fasthttp server) on an http request and then adding it >> into this structure, most of the times is just a 5 char string. Out of >> several millions requests, this panic happens. > > Does this "fasthttp" have any unsafe pointers? > > >> >> I failed to find any kind of race using go race detector, I'm currently >> doing some more debugging, hopefuly I should have more info/tests soon. >> >> El jueves, 2 de mayo de 2019, 20:44:33 (UTC-3), Burak Serdar escribió: >>> >>> On Thu, May 2, 2019 at 3:56 PM Ian Lance Taylor <ia...@golang.org> wrote: >>>> >>>>> On Thu, May 2, 2019 at 2:50 PM Anthony Martin <al...@pbrane.org> wrote: >>>>> >>>>> What version of Go are you using? >>>>> >>>>> XXX ZZZ <emarti...@gmail.com> once said: >>>>>> fmt.(*pp).fmtString(0xc023c17740, 0x0, 0x5, 0xc000000076) >>>>>> /usr/local/go/src/fmt/print.go:448 +0x132 >>>>>> fmt.(*pp).printArg(0xc023c17740, 0x9978e0, 0xc016a68a30, 0x76) >>>>>> /usr/local/go/src/fmt/print.go:684 +0x880 >>>>>> fmt.(*pp).doPrintf(0xc023c17740, 0xa6e22f, 0x5, 0xc048c27818, 0x1, 0x1) >>>>>> /usr/local/go/src/fmt/print.go:1112 +0x3ff >>>>>> fmt.Sprintf(0xa6e22f, 0x5, 0xc048c27818, 0x1, 0x1, 0x80, 0xa36200) >>>>>> /usr/local/go/src/fmt/print.go:214 +0x66 >>>>> >>>>> This shows signs of memory corruption. The last argument passed to >>>>> fmtString (0xc000000076) should be the same as the last argument >>>>> passed to printArg (0x76 or 'v') but it has some high bits set. Also, >>>>> the pointer to the format string data changes from 0xa6e22f (which is >>>>> probably in the .rodata section of the binary) to 0x0. >>>>> >>>>> Something is amiss. >>>> >>>> The change from 0x76 to 0xc000000076 does not necessarily indicate a >>>> problem. The stack backtrace does not know the types. The value here >>>> is a rune, which is 32 bits. The compiler will only set the low order >>>> 32 bits on the stack, leaving the high order 32 bits unset. So the >>>> 0xc000000000 could just be garbage left on the stack. >>>> >>>> I don't *think* the format string is changing. I think the 0 is from >>>> the string being printed, not the format string. They both happen to >>>> be length 5. >>> >>> There's something that doesn't make sense here. The 0 is from the >>> string being printed, it is not the format string. But how can that >>> be? >>> >>> Even if there is a race, the string cannot have a 0 for the slice, can >>> it? So the other option is when Sprintf is called, the string being >>> printed is already corrupt. Can there be an overflow somewhere that is >>> somehow undetected? Any unsafe use in the program? >>> >>> >>>> >>>> Ian >>>> >>>> -- >>>> 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 golan...@googlegroups.com. >>>> For more options, visit https://groups.google.com/d/optout. >> >> -- >> 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. >> For more options, visit https://groups.google.com/d/optout. > > -- > 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. > For more options, visit https://groups.google.com/d/optout. -- 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. For more options, visit https://groups.google.com/d/optout.
