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-rw-r--r--fs/proc/base.c22
1 files changed, 11 insertions, 11 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c
index f3c2e4085fed..175db258942f 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -234,19 +234,19 @@ static int check_mem_permission(struct task_struct *task)
struct mm_struct *mm_for_maps(struct task_struct *task)
{
- struct mm_struct *mm = get_task_mm(task);
+ struct mm_struct *mm;
- if (mm && mm != current->mm) {
- /*
- * task->mm can be changed before security check,
- * in that case we must notice the change after.
- */
- if (!ptrace_may_access(task, PTRACE_MODE_READ) ||
- mm != task->mm) {
- mmput(mm);
- mm = NULL;
- }
+ if (mutex_lock_killable(&task->cred_guard_mutex))
+ return NULL;
+
+ mm = get_task_mm(task);
+ if (mm && mm != current->mm &&
+ !ptrace_may_access(task, PTRACE_MODE_READ)) {
+ mmput(mm);
+ mm = NULL;
}
+ mutex_unlock(&task->cred_guard_mutex);
+
return mm;
}