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-rw-r--r--fs/file.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/fs/file.c b/fs/file.c
index 3d2eb4c542a4..6c672ad329e9 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -664,11 +664,17 @@ static struct file *__fget(unsigned int fd, fmode_t mask)
struct file *file;
rcu_read_lock();
+loop:
file = fcheck_files(files, fd);
if (file) {
- /* File object ref couldn't be taken */
- if ((file->f_mode & mask) || !get_file_rcu(file))
+ /* File object ref couldn't be taken.
+ * dup2() atomicity guarantee is the reason
+ * we loop to catch the new file (or NULL pointer)
+ */
+ if (file->f_mode & mask)
file = NULL;
+ else if (!get_file_rcu(file))
+ goto loop;
}
rcu_read_unlock();