From d3747c722655480e783b482c959331238997733f Mon Sep 17 00:00:00 2001 From: Dmitry Vyukov Date: Sun, 25 Oct 2020 12:12:10 +0100 Subject: pkg/csource: setup sysctl's in C reproducers Sysctl's are not captured as part of reproducers. This can result in failure to reproduce a bug on developer machine. Include sysctl setup as part of C reproducers. --- executor/common_linux.h | 40 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) (limited to 'executor/common_linux.h') diff --git a/executor/common_linux.h b/executor/common_linux.h index 1d372af7f..11ce0a6e9 100644 --- a/executor/common_linux.h +++ b/executor/common_linux.h @@ -4578,6 +4578,46 @@ static void setup_usb() } #endif +#if SYZ_EXECUTOR || SYZ_SYSCTL +static void setup_sysctl() +{ + static struct { + const char* name; + const char* data; + } files[] = { + // nmi_check_duration() prints "INFO: NMI handler took too long" on slow debug kernels. + // It happens a lot in qemu, and the messages are frequently corrupted + // (intermixed with other kernel output as they are printed from NMI) + // and are not matched against the suppression in pkg/report. + // This write prevents these messages from being printed. + {"/sys/kernel/debug/x86/nmi_longest_ns", "10000000000"}, + // This is part of deterministic hang/stall detection. + // Don't change this without considering workqueue.watchdog_thresh, + // CONFIG_RCU_CPU_STALL_TIMEOUT and CONFIG_DEFAULT_HUNG_TASK_TIMEOUT. + {"/proc/sys/kernel/watchdog_thresh", "55"}, + {"/proc/sys/kernel/hung_task_check_interval_secs", "20"}, + // This gives more interesting coverage. + {"/proc/sys/net/core/bpf_jit_enable", "1"}, + // bpf_jit_kallsyms and disabling bpf_jit_harden are required + // for unwinding through bpf functions. + {"/proc/sys/net/core/bpf_jit_kallsyms", "1"}, + {"/proc/sys/net/core/bpf_jit_harden", "0"}, + // This is to provide more useful info in crash reports. + {"/proc/sys/kernel/kptr_restrict", "0"}, + {"/proc/sys/kernel/softlockup_all_cpu_backtrace", "1"}, + // This is to restrict effects of recursive exponential mounts, for details see + // "mnt: Add a per mount namespace limit on the number of mounts" commit. + {"/proc/sys/fs/mount-max", "100"}, + // Dumping all tasks to console can take too long. + {"/proc/sys/vm/oom_dump_tasks", "0"}, + }; + for (size_t i = 0; i < sizeof(files) / sizeof(files[0]); i++) { + if (!write_file(files[i].name, files[i].data)) + printf("write to %s failed: %s\n", files[i].name, strerror(errno)); + } +} +#endif + #if GOARCH_s390x #include // Ugly way to work around gcc's "error: function called through a non-compatible type". -- cgit mrf-deployment