proc: fix coredump vs read /proc/*/stat race

[mirror_ubuntu-bionic-kernel.git] / fs / proc / array.c

diff --git a/fs/proc/array.c b/fs/proc/array.c
index 9390032a11e13d559b0fbc9accbee25bdff38b30..d67a72dcb92c47865177c2243231572f040c3cf6 100644 (file)
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -138,7 +138,7 @@ static const char * const task_state_array[] = {
 static inline const char *get_task_state(struct task_struct *tsk)
 {
        BUILD_BUG_ON(1 + ilog2(TASK_REPORT_MAX) != ARRAY_SIZE(task_state_array));
-       return task_state_array[__get_task_state(tsk)];
+       return task_state_array[task_state_index(tsk)];
 }
 
 static inline int get_task_umask(struct task_struct *tsk)
@@ -366,6 +366,11 @@ static void task_cpus_allowed(struct seq_file *m, struct task_struct *task)
                   cpumask_pr_args(&task->cpus_allowed));
 }
 
+static inline void task_core_dumping(struct seq_file *m, struct mm_struct *mm)
+{
+       seq_printf(m, "CoreDumping:\t%d\n", !!mm->core_state);
+}
+
 int proc_pid_status(struct seq_file *m, struct pid_namespace *ns,
                        struct pid *pid, struct task_struct *task)
 {
@@ -376,6 +381,7 @@ int proc_pid_status(struct seq_file *m, struct pid_namespace *ns,
 
        if (mm) {
                task_mem(m, mm);
+               task_core_dumping(m, mm);
                mmput(mm);
        }
        task_sig(m, task);
@@ -424,8 +430,11 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
                 * safe because the task has stopped executing permanently.
                 */
                if (permitted && (task->flags & PF_DUMPCORE)) {
-                       eip = KSTK_EIP(task);
-                       esp = KSTK_ESP(task);
+                       if (try_get_task_stack(task)) {
+                               eip = KSTK_EIP(task);
+                               esp = KSTK_ESP(task);
+                               put_task_stack(task);
+                       }
                }
        }
 
@@ -454,7 +463,7 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
                cutime = sig->cutime;
                cstime = sig->cstime;
                cgtime = sig->cgtime;
-               rsslim = ACCESS_ONCE(sig->rlim[RLIMIT_RSS].rlim_cur);
+               rsslim = READ_ONCE(sig->rlim[RLIMIT_RSS].rlim_cur);
 
                /* add up live thread stats at the group level */
                if (whole) {