--- /dev/null
+From 158b515f703e75e7d68289bf4d98c664e1d632df Mon Sep 17 00:00:00 2001
+From: George Kennedy <george.kennedy@oracle.com>
+Date: Thu, 16 Dec 2021 13:25:32 -0500
+Subject: tun: avoid double free in tun_free_netdev
+
+From: George Kennedy <george.kennedy@oracle.com>
+
+commit 158b515f703e75e7d68289bf4d98c664e1d632df upstream.
+
+Avoid double free in tun_free_netdev() by moving the
+dev->tstats and tun->security allocs to a new ndo_init routine
+(tun_net_init()) that will be called by register_netdevice().
+ndo_init is paired with the desctructor (tun_free_netdev()),
+so if there's an error in register_netdevice() the destructor
+will handle the frees.
+
+BUG: KASAN: double-free or invalid-free in selinux_tun_dev_free_security+0x1a/0x20 security/selinux/hooks.c:5605
+
+CPU: 0 PID: 25750 Comm: syz-executor416 Not tainted 5.16.0-rc2-syzk #1
+Hardware name: Red Hat KVM, BIOS
+Call Trace:
+<TASK>
+__dump_stack lib/dump_stack.c:88 [inline]
+dump_stack_lvl+0x89/0xb5 lib/dump_stack.c:106
+print_address_description.constprop.9+0x28/0x160 mm/kasan/report.c:247
+kasan_report_invalid_free+0x55/0x80 mm/kasan/report.c:372
+____kasan_slab_free mm/kasan/common.c:346 [inline]
+__kasan_slab_free+0x107/0x120 mm/kasan/common.c:374
+kasan_slab_free include/linux/kasan.h:235 [inline]
+slab_free_hook mm/slub.c:1723 [inline]
+slab_free_freelist_hook mm/slub.c:1749 [inline]
+slab_free mm/slub.c:3513 [inline]
+kfree+0xac/0x2d0 mm/slub.c:4561
+selinux_tun_dev_free_security+0x1a/0x20 security/selinux/hooks.c:5605
+security_tun_dev_free_security+0x4f/0x90 security/security.c:2342
+tun_free_netdev+0xe6/0x150 drivers/net/tun.c:2215
+netdev_run_todo+0x4df/0x840 net/core/dev.c:10627
+rtnl_unlock+0x13/0x20 net/core/rtnetlink.c:112
+__tun_chr_ioctl+0x80c/0x2870 drivers/net/tun.c:3302
+tun_chr_ioctl+0x2f/0x40 drivers/net/tun.c:3311
+vfs_ioctl fs/ioctl.c:51 [inline]
+__do_sys_ioctl fs/ioctl.c:874 [inline]
+__se_sys_ioctl fs/ioctl.c:860 [inline]
+__x64_sys_ioctl+0x19d/0x220 fs/ioctl.c:860
+do_syscall_x64 arch/x86/entry/common.c:50 [inline]
+do_syscall_64+0x3a/0x80 arch/x86/entry/common.c:80
+entry_SYSCALL_64_after_hwframe+0x44/0xae
+
+Reported-by: syzkaller <syzkaller@googlegroups.com>
+Signed-off-by: George Kennedy <george.kennedy@oracle.com>
+Suggested-by: Jakub Kicinski <kuba@kernel.org>
+Link: https://lore.kernel.org/r/1639679132-19884-1-git-send-email-george.kennedy@oracle.com
+Signed-off-by: Jakub Kicinski <kuba@kernel.org>
+[DP: adjusted context for 5.4 stable]
+Signed-off-by: Dragos-Marian Panait <dragos.panait@windriver.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ drivers/net/tun.c | 109 +++++++++++++++++++++++++++++-------------------------
+ 1 file changed, 59 insertions(+), 50 deletions(-)
+
+--- a/drivers/net/tun.c
++++ b/drivers/net/tun.c
+@@ -250,6 +250,9 @@ struct tun_struct {
+ struct tun_prog __rcu *steering_prog;
+ struct tun_prog __rcu *filter_prog;
+ struct ethtool_link_ksettings link_ksettings;
++ /* init args */
++ struct file *file;
++ struct ifreq *ifr;
+ };
+
+ struct veth {
+@@ -275,6 +278,9 @@ void *tun_ptr_to_xdp(void *ptr)
+ }
+ EXPORT_SYMBOL(tun_ptr_to_xdp);
+
++static void tun_flow_init(struct tun_struct *tun);
++static void tun_flow_uninit(struct tun_struct *tun);
++
+ static int tun_napi_receive(struct napi_struct *napi, int budget)
+ {
+ struct tun_file *tfile = container_of(napi, struct tun_file, napi);
+@@ -1027,6 +1033,49 @@ static int check_filter(struct tap_filte
+
+ static const struct ethtool_ops tun_ethtool_ops;
+
++static int tun_net_init(struct net_device *dev)
++{
++ struct tun_struct *tun = netdev_priv(dev);
++ struct ifreq *ifr = tun->ifr;
++ int err;
++
++ tun->pcpu_stats = netdev_alloc_pcpu_stats(struct tun_pcpu_stats);
++ if (!tun->pcpu_stats)
++ return -ENOMEM;
++
++ spin_lock_init(&tun->lock);
++
++ err = security_tun_dev_alloc_security(&tun->security);
++ if (err < 0) {
++ free_percpu(tun->pcpu_stats);
++ return err;
++ }
++
++ tun_flow_init(tun);
++
++ dev->hw_features = NETIF_F_SG | NETIF_F_FRAGLIST |
++ TUN_USER_FEATURES | NETIF_F_HW_VLAN_CTAG_TX |
++ NETIF_F_HW_VLAN_STAG_TX;
++ dev->features = dev->hw_features | NETIF_F_LLTX;
++ dev->vlan_features = dev->features &
++ ~(NETIF_F_HW_VLAN_CTAG_TX |
++ NETIF_F_HW_VLAN_STAG_TX);
++
++ tun->flags = (tun->flags & ~TUN_FEATURES) |
++ (ifr->ifr_flags & TUN_FEATURES);
++
++ INIT_LIST_HEAD(&tun->disabled);
++ err = tun_attach(tun, tun->file, false, ifr->ifr_flags & IFF_NAPI,
++ ifr->ifr_flags & IFF_NAPI_FRAGS, false);
++ if (err < 0) {
++ tun_flow_uninit(tun);
++ security_tun_dev_free_security(tun->security);
++ free_percpu(tun->pcpu_stats);
++ return err;
++ }
++ return 0;
++}
++
+ /* Net device detach from fd. */
+ static void tun_net_uninit(struct net_device *dev)
+ {
+@@ -1285,6 +1334,7 @@ static int tun_net_change_carrier(struct
+ }
+
+ static const struct net_device_ops tun_netdev_ops = {
++ .ndo_init = tun_net_init,
+ .ndo_uninit = tun_net_uninit,
+ .ndo_open = tun_net_open,
+ .ndo_stop = tun_net_close,
+@@ -1365,6 +1415,7 @@ static int tun_xdp_tx(struct net_device
+ }
+
+ static const struct net_device_ops tap_netdev_ops = {
++ .ndo_init = tun_net_init,
+ .ndo_uninit = tun_net_uninit,
+ .ndo_open = tun_net_open,
+ .ndo_stop = tun_net_close,
+@@ -1405,7 +1456,7 @@ static void tun_flow_uninit(struct tun_s
+ #define MAX_MTU 65535
+
+ /* Initialize net device. */
+-static void tun_net_init(struct net_device *dev)
++static void tun_net_initialize(struct net_device *dev)
+ {
+ struct tun_struct *tun = netdev_priv(dev);
+
+@@ -2839,9 +2890,6 @@ static int tun_set_iff(struct net *net,
+
+ if (!dev)
+ return -ENOMEM;
+- err = dev_get_valid_name(net, dev, name);
+- if (err < 0)
+- goto err_free_dev;
+
+ dev_net_set(dev, net);
+ dev->rtnl_link_ops = &tun_link_ops;
+@@ -2860,41 +2908,16 @@ static int tun_set_iff(struct net *net,
+ tun->rx_batched = 0;
+ RCU_INIT_POINTER(tun->steering_prog, NULL);
+
+- tun->pcpu_stats = netdev_alloc_pcpu_stats(struct tun_pcpu_stats);
+- if (!tun->pcpu_stats) {
+- err = -ENOMEM;
+- goto err_free_dev;
+- }
+-
+- spin_lock_init(&tun->lock);
+-
+- err = security_tun_dev_alloc_security(&tun->security);
+- if (err < 0)
+- goto err_free_stat;
+-
+- tun_net_init(dev);
+- tun_flow_init(tun);
++ tun->ifr = ifr;
++ tun->file = file;
+
+- dev->hw_features = NETIF_F_SG | NETIF_F_FRAGLIST |
+- TUN_USER_FEATURES | NETIF_F_HW_VLAN_CTAG_TX |
+- NETIF_F_HW_VLAN_STAG_TX;
+- dev->features = dev->hw_features | NETIF_F_LLTX;
+- dev->vlan_features = dev->features &
+- ~(NETIF_F_HW_VLAN_CTAG_TX |
+- NETIF_F_HW_VLAN_STAG_TX);
+-
+- tun->flags = (tun->flags & ~TUN_FEATURES) |
+- (ifr->ifr_flags & TUN_FEATURES);
+-
+- INIT_LIST_HEAD(&tun->disabled);
+- err = tun_attach(tun, file, false, ifr->ifr_flags & IFF_NAPI,
+- ifr->ifr_flags & IFF_NAPI_FRAGS, false);
+- if (err < 0)
+- goto err_free_flow;
++ tun_net_initialize(dev);
+
+ err = register_netdevice(tun->dev);
+- if (err < 0)
+- goto err_detach;
++ if (err < 0) {
++ free_netdev(dev);
++ return err;
++ }
+ /* free_netdev() won't check refcnt, to aovid race
+ * with dev_put() we need publish tun after registration.
+ */
+@@ -2913,20 +2936,6 @@ static int tun_set_iff(struct net *net,
+
+ strcpy(ifr->ifr_name, tun->dev->name);
+ return 0;
+-
+-err_detach:
+- tun_detach_all(dev);
+- /* register_netdevice() already called tun_free_netdev() */
+- goto err_free_dev;
+-
+-err_free_flow:
+- tun_flow_uninit(tun);
+- security_tun_dev_free_security(tun->security);
+-err_free_stat:
+- free_percpu(tun->pcpu_stats);
+-err_free_dev:
+- free_netdev(dev);
+- return err;
+ }
+
+ static void tun_get_iff(struct tun_struct *tun, struct ifreq *ifr)
projects / thirdparty / kernel / stable-queue.git / commitdiff
