On Fri, Dec 4, 2015 at 9:32 PM, Alexei Starovoitov <alexei.starovoi...@gmail.com> wrote: > On Fri, Dec 04, 2015 at 09:04:35PM +0100, Dmitry Vyukov wrote: >> Hello, >> >> While running syzkaller fuzzer I am seeing lots of the following >> use-after-free reports. Unfortunately all my numerous attempts to >> reproduce them in a controlled environment failed. They pop up during >> fuzzing periodically (once in several hours in a single VM), but >> whenever I try to stress-replay what happened in the VM before the >> report, the use-after-free does not reproduce. Can somebody >> knowledgeable in perf subsystem look at the report? Maybe it is >> possible to figure out what happened based purely on the report. I can >> pretty reliably test any proposed fixes. >> All reports look like this one. Then it is usually followed by other >> reports and eventually kernel hangs or dies. What happens in the >> fuzzer is essentially random syscalls with random arguments, tasks >> born and die concurrently and so on. I was able to reproduce it by >> restricting syscalls only to perf_event_open, perf ioctls and bpf >> syscall. > > For the sake of trying to narrow it down: > does the error disappear when you stop using bpf syscall in your fuzzing? > If yes, then I could have missed some interaction between perf_event_free, > kprobe free and bpf_prog_free. > There was a race there before. > May be there is still something else.
It is a good question. I will test it. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
