From: Ziyang Xuan william.xuanziyang@huawei.com
commit 196a888ca6571deb344468e1d7138e3273206335 upstream.
Create a new macsec device but not get reference to real_dev. That can not ensure that real_dev is freed after macsec. That will trigger the UAF bug for real_dev as following:
================================================================== BUG: KASAN: use-after-free in macsec_get_iflink+0x5f/0x70 drivers/net/macsec.c:3662 Call Trace: ... macsec_get_iflink+0x5f/0x70 drivers/net/macsec.c:3662 dev_get_iflink+0x73/0xe0 net/core/dev.c:637 default_operstate net/core/link_watch.c:42 [inline] rfc2863_policy+0x233/0x2d0 net/core/link_watch.c:54 linkwatch_do_dev+0x2a/0x150 net/core/link_watch.c:161
Allocated by task 22209: ... alloc_netdev_mqs+0x98/0x1100 net/core/dev.c:10549 rtnl_create_link+0x9d7/0xc00 net/core/rtnetlink.c:3235 veth_newlink+0x20e/0xa90 drivers/net/veth.c:1748
Freed by task 8: ... kfree+0xd6/0x4d0 mm/slub.c:4552 kvfree+0x42/0x50 mm/util.c:615 device_release+0x9f/0x240 drivers/base/core.c:2229 kobject_cleanup lib/kobject.c:673 [inline] kobject_release lib/kobject.c:704 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x1c8/0x540 lib/kobject.c:721 netdev_run_todo+0x72e/0x10b0 net/core/dev.c:10327
After commit faab39f63c1f ("net: allow out-of-order netdev unregistration") and commit e5f80fcf869a ("ipv6: give an IPv6 dev to blackhole_netdev"), we can add dev_hold_track() in macsec_dev_init() and dev_put_track() in macsec_free_netdev() to fix the problem.
Fixes: 2bce1ebed17d ("macsec: fix refcnt leak in module exit routine") Reported-by: syzbot+d0e94b65ac259c29ce7a@syzkaller.appspotmail.com Signed-off-by: Ziyang Xuan william.xuanziyang@huawei.com Link: https://lore.kernel.org/r/20220531074500.1272846-1-william.xuanziyang@huawei... Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/macsec.c | 7 +++++++ 1 file changed, 7 insertions(+)
--- a/drivers/net/macsec.c +++ b/drivers/net/macsec.c @@ -99,6 +99,7 @@ struct pcpu_secy_stats { * struct macsec_dev - private data * @secy: SecY config * @real_dev: pointer to underlying netdevice + * @dev_tracker: refcount tracker for @real_dev reference * @stats: MACsec device stats * @secys: linked list of SecY's on the underlying device * @gro_cells: pointer to the Generic Receive Offload cell @@ -107,6 +108,7 @@ struct pcpu_secy_stats { struct macsec_dev { struct macsec_secy secy; struct net_device *real_dev; + netdevice_tracker dev_tracker; struct pcpu_secy_stats __percpu *stats; struct list_head secys; struct gro_cells gro_cells; @@ -3459,6 +3461,9 @@ static int macsec_dev_init(struct net_de if (is_zero_ether_addr(dev->broadcast)) memcpy(dev->broadcast, real_dev->broadcast, dev->addr_len);
+ /* Get macsec's reference to real_dev */ + dev_hold_track(real_dev, &macsec->dev_tracker, GFP_KERNEL); + return 0; }
@@ -3704,6 +3709,8 @@ static void macsec_free_netdev(struct ne free_percpu(macsec->stats); free_percpu(macsec->secy.tx_sc.stats);
+ /* Get rid of the macsec's reference to real_dev */ + dev_put_track(macsec->real_dev, &macsec->dev_tracker); }
static void macsec_setup(struct net_device *dev)