[PATCH AUTOSEL 4.19 09/15] proc: don't allow async path resolution of /proc/self components

Sasha Levin
2020-11-25T15:37:40Z

From: Jens Axboe <axboe@kernel.dk>

[ Upstream commit 8d4c3e76e3be11a64df95ddee52e99092d42fc19 ]

If this is attempted by a kthread, then return -EOPNOTSUPP as we don't
currently support that. Once we can get task_pid_ptr() doing the right
thing, then this can go away again.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/proc/self.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/fs/proc/self.c b/fs/proc/self.c
index cc6d4253399d1..7922edf70ce1a 100644
--- a/fs/proc/self.c
+++ b/fs/proc/self.c
@@ -16,6 +16,13 @@ static const char *proc_self_get_link(struct dentry *dentry,
pid_t tgid = task_tgid_nr_ns(current, ns);
char *name;

+ /*
+ * Not currently supported. Once we can inherit all of struct pid,
+ * we can allow this.
+ */
+ if (current->flags & PF_KTHREAD)
+ return ERR_PTR(-EOPNOTSUPP);
+
if (!tgid)
return ERR_PTR(-ENOENT);
/* max length of unsigned int in decimal + NULL term */
--
2.27.0