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From: Changbin Du <>
To: Alexander Viro <>
Cc: "David S. Miller" <>,
	Jakub Kici nski <>,,,,
	Changbin Du <>,
	Cong Wang <>,
	David Laight <David.Laight@ACULAB.COM>,
	Christian Brauner <>
Subject: [RESEND PATCH v2] nsfs: warn if ns->ops is not provided
Date: Sun, 20 Jun 2021 10:52:38 +0800	[thread overview]
Message-ID: <> (raw)

We should not create inode for disabled namespace. A disabled namespace
sets its ns->ops to NULL. Kernel could panic if we try to create a inode
for such namespace.

Here is an example oops in socket ioctl cmd SIOCGSKNS when NET_NS is
disabled. Kernel panicked wherever nsfs trys to access ns->ops since the
proc_ns_operations is not implemented in this case.

[7.670023] Unable to handle kernel NULL pointer dereference at virtual address 00000010
[7.670268] pgd = 32b54000
[7.670544] [00000010] *pgd=00000000
[7.671861] Internal error: Oops: 5 [#1] SMP ARM
[7.672315] Modules linked in:
[7.672918] CPU: 0 PID: 1 Comm: systemd Not tainted 5.13.0-rc3-00375-g6799d4f2da49 #16
[7.673309] Hardware name: Generic DT based system
[7.673642] PC is at nsfs_evict+0x24/0x30
[7.674486] LR is at clear_inode+0x20/0x9c

So let's print a warning for such unexpected request which to create the
nsfs inode. The issue in networking will be fixed in another change.

Signed-off-by: Changbin Du <>
Cc: Cong Wang <>
Cc: Jakub Kicinski <>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: Christian Brauner <>
 fs/nsfs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/nsfs.c b/fs/nsfs.c
index 800c1d0eb0d0..a132827bddd5 100644
--- a/fs/nsfs.c
+++ b/fs/nsfs.c
@@ -62,6 +62,9 @@ static int __ns_get_path(struct path *path, struct ns_common *ns)
 	struct inode *inode;
 	unsigned long d;
+	if (WARN_ON_ONCE(!ns->ops))
+		return -EINVAL;
 	d = atomic_long_read(&ns->stashed);
 	if (!d)

                 reply	other threads:[~2021-06-20  2:52 UTC|newest]

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