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authorYong He <chenglang.hy@antfin.com>2019-06-12 21:13:13 +0800
committerYong He <chenglang.hy@antfin.com>2019-06-14 14:05:41 +0800
commit0dbdca349cd90fff4353650efcb0198b4ad6cb6d (patch)
treeb7d08f170e32beadf11651ce9e066d450953951f /test/syscalls/linux/temp_umask.h
parentdf110ad4fe571721a7eb4a5a1f9ce92584ef7809 (diff)
Skip tid allocation which is using
When leader of process group (session) exit, the process group ID (session ID) is holding by other processes in the process group, so the process group ID (session ID) can not be reused. If reusing the process group ID (seession ID) as new process group ID for new process, this will cause session create failed, and later runsc crash when access process group. The fix skip the tid if it is using by a process group (session) when allocating a new tid. We could easily reproduce the runsc crash follow these steps: 1. build test program, and run inside container int main(int argc, char *argv[]) { pid_t cpid, spid; cpid = fork(); if (cpid == -1) { perror("fork"); exit(EXIT_FAILURE); } if (cpid == 0) { pid_t sid = setsid(); printf("Start New Session %ld\n",sid); printf("Child PID %ld / PPID %ld / PGID %ld / SID %ld\n", getpid(),getppid(),getpgid(getpid()),getsid(getpid())); spid = fork(); if (spid == 0) { setpgid(getpid(), getpid()); printf("Set GrandSon as New Process Group\n"); printf("GrandSon PID %ld / PPID %ld / PGID %ld / SID %ld\n", getpid(),getppid(),getpgid(getpid()),getsid(getpid())); while(1) { usleep(1); } } sleep(3); exit(0); } else { exit(0); } return 0; } 2. build hello program int main(int argc, char *argv[]) { printf("Current PID is %ld\n", (long) getpid()); return 0; } 3. run script on host which run hello inside container, you can speed up the test with set TasksLimit as lower value. for (( i=0; i<65535; i++ )) do docker exec <container id> /test/hello done 4. when hello process reusing the process group of loop process, runsc will crash. panic: runtime error: invalid memory address or nil pointer dereference [signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x79f0c8] goroutine 612475 [running]: gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*ProcessGroup).decRefWithParent(0x0, 0x0) pkg/sentry/kernel/sessions.go:160 +0x78 gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*Task).exitNotifyLocked(0xc000663500, 0x0) pkg/sentry/kernel/task_exit.go:672 +0x2b7 gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*runExitNotify).execute(0x0, 0xc000663500, 0x0, 0x0) pkg/sentry/kernel/task_exit.go:542 +0xc4 gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*Task).run(0xc000663500, 0xc) pkg/sentry/kernel/task_run.go:91 +0x194 created by gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*Task).Start pkg/sentry/kernel/task_start.go:286 +0xfe
Diffstat (limited to 'test/syscalls/linux/temp_umask.h')
0 files changed, 0 insertions, 0 deletions