| Message ID | 20211101040103.388646-1-mudongliangabcd@gmail.com |
|---|---|
| State | Rejected, archived |
| Delegated to: | Simon Wunderlich |
| Headers | show |
| Series | net: batman-adv: fix warning in batadv_v_ogm_free | expand |
On Monday, 1 November 2021 05:01:02 CET Dongliang Mu wrote: > Call Trace: > __cancel_work_timer+0x1c9/0x280 kernel/workqueue.c:3170 > batadv_v_ogm_free+0x1d/0x50 net/batman-adv/bat_v_ogm.c:1076 > batadv_mesh_free+0x35/0xa0 net/batman-adv/main.c:244 > batadv_mesh_init+0x22a/0x240 net/batman-adv/main.c:226 > batadv_softif_init_late+0x1ad/0x240 net/batman-adv/soft-interface.c:804 > register_netdevice+0x15d/0x810 net/core/dev.c:10229 This is definitely not a backtrace of the current code and its error handling. Please check the current code [1] and explain the situation against this version. Kind regards, Sven [1] https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/tree/net/batman-adv/main.c?id=ae0393500e3b0139210749d52d22b29002c20e16#n237
On Mon, Nov 1, 2021 at 3:46 PM Sven Eckelmann <sven@narfation.org> wrote: > > On Monday, 1 November 2021 05:01:02 CET Dongliang Mu wrote: > > Call Trace: > > __cancel_work_timer+0x1c9/0x280 kernel/workqueue.c:3170 > > batadv_v_ogm_free+0x1d/0x50 net/batman-adv/bat_v_ogm.c:1076 > > batadv_mesh_free+0x35/0xa0 net/batman-adv/main.c:244 > > batadv_mesh_init+0x22a/0x240 net/batman-adv/main.c:226 > > batadv_softif_init_late+0x1ad/0x240 net/batman-adv/soft-interface.c:804 > > register_netdevice+0x15d/0x810 net/core/dev.c:10229 > > This is definitely not a backtrace of the current code and its error handling. > Please check the current code [1] and explain the situation against this > version. Yes, you're right. The error handling code in the upstream is not prone to this bug. My local syzkaller instance is fuzzing on 5.14-rc5 > > Kind regards, > Sven > > [1] https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/tree/net/batman-adv/main.c?id=ae0393500e3b0139210749d52d22b29002c20e16#n237
diff --git a/net/batman-adv/bat_v_ogm.c b/net/batman-adv/bat_v_ogm.c index 1d750f3cb2e4..2f3ecbcec58d 100644 --- a/net/batman-adv/bat_v_ogm.c +++ b/net/batman-adv/bat_v_ogm.c @@ -1044,6 +1044,13 @@ int batadv_v_ogm_init(struct batadv_priv *bat_priv) unsigned char *ogm_buff; u32 random_seqno; + /* randomize initial seqno to avoid collision */ + get_random_bytes(&random_seqno, sizeof(random_seqno)); + atomic_set(&bat_priv->bat_v.ogm_seqno, random_seqno); + INIT_DELAYED_WORK(&bat_priv->bat_v.ogm_wq, batadv_v_ogm_send); + + mutex_init(&bat_priv->bat_v.ogm_buff_mutex); + bat_priv->bat_v.ogm_buff_len = BATADV_OGM2_HLEN; ogm_buff = kzalloc(bat_priv->bat_v.ogm_buff_len, GFP_ATOMIC); if (!ogm_buff) @@ -1057,13 +1064,6 @@ int batadv_v_ogm_init(struct batadv_priv *bat_priv) ogm_packet->flags = BATADV_NO_FLAGS; ogm_packet->throughput = htonl(BATADV_THROUGHPUT_MAX_VALUE); - /* randomize initial seqno to avoid collision */ - get_random_bytes(&random_seqno, sizeof(random_seqno)); - atomic_set(&bat_priv->bat_v.ogm_seqno, random_seqno); - INIT_DELAYED_WORK(&bat_priv->bat_v.ogm_wq, batadv_v_ogm_send); - - mutex_init(&bat_priv->bat_v.ogm_buff_mutex); - return 0; }
If batadv_v_ogm_init encounters a memory failure, the fields ogm_wq, ogm_buff_mutex and etc. are not initialized. Then the control flow goes to batadv_v_ogm_free due to the error handling code. As a result, the API invocation "cancel_delayed_work_sync" and "mutex_lock" will cause many issues. The crashing stack trace is as follows: Call Trace: __cancel_work_timer+0x1c9/0x280 kernel/workqueue.c:3170 batadv_v_ogm_free+0x1d/0x50 net/batman-adv/bat_v_ogm.c:1076 batadv_mesh_free+0x35/0xa0 net/batman-adv/main.c:244 batadv_mesh_init+0x22a/0x240 net/batman-adv/main.c:226 batadv_softif_init_late+0x1ad/0x240 net/batman-adv/soft-interface.c:804 register_netdevice+0x15d/0x810 net/core/dev.c:10229 Fixes: a8d23cbbf6c9 ("batman-adv: Avoid free/alloc race when handling OGM2 buffer") Fixes: 0da0035942d4 ("batman-adv: OGMv2 - add basic infrastructure") Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com> --- net/batman-adv/bat_v_ogm.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-)