[PATCH v2] net: do not invoke open_related_ns when NET_NS is disabled
From: Changbin Du <hidden>
Date: 2021-06-09 15:46:54
When NET_NS is not enabled, socket ioctl cmd SIOCGSKNS should do nothing but acknowledge userspace it is not supported. Otherwise, kernel would panic 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 The same to tun SIOCGSKNS command. Signed-off-by: Changbin Du <redacted> Cc: Cong Wang <redacted> Cc: Jakub Kicinski <kuba@kernel.org> Cc: David Laight <redacted> Cc: Christian Brauner <redacted> --- drivers/net/tun.c | 4 ++++ net/socket.c | 4 ++++ 2 files changed, 8 insertions(+)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 84f832806313..8ec5977d2f34 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c@@ -3003,9 +3003,13 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd, } else if (cmd == TUNSETQUEUE) { return tun_set_queue(file, &ifr); } else if (cmd == SIOCGSKNS) { +#ifdef CONFIG_NET_NS if (!ns_capable(net->user_ns, CAP_NET_ADMIN)) return -EPERM; return open_related_ns(&net->ns, get_net_ns); +#else + return -EOPNOTSUPP; +#endif } rtnl_lock();
diff --git a/net/socket.c b/net/socket.c
index 27e3e7d53f8e..bc644030d2e8 100644
--- a/net/socket.c
+++ b/net/socket.c@@ -1149,11 +1149,15 @@ static long sock_ioctl(struct file *file, unsigned cmd, unsigned long arg) mutex_unlock(&vlan_ioctl_mutex); break; case SIOCGSKNS: +#ifdef CONFIG_NET_NS err = -EPERM; if (!ns_capable(net->user_ns, CAP_NET_ADMIN)) break; err = open_related_ns(&net->ns, get_net_ns); +#else + err = -EOPNOTSUPP; +#endif break; case SIOCGSTAMP_OLD: case SIOCGSTAMPNS_OLD:
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2.30.2