From: Jens Axboe <axboe@kernel.dk>
Date: Fri, 13 Nov 2020 23:47:52 +0000 (-0700)
Subject: proc: don't allow async path resolution of /proc/self components
X-Git-Tag: v4.14.210~31
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=f95a1253d79449da7d0f06eab1feca4530e3b813;p=users%2Fdwmw2%2Flinux.git

proc: don't allow async path resolution of /proc/self components

[ 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>
---

diff --git a/fs/proc/self.c b/fs/proc/self.c
index 398cdf9a9f0c6..eba167e1700ef 100644
--- a/fs/proc/self.c
+++ b/fs/proc/self.c
@@ -15,6 +15,13 @@ 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);
 	/* 11 for max length of signed int in decimal + NULL term */