On 8/25/20 11:52 PM, Hoang Huu Le wrote:
Syzbot has reported those issues as: ================================================================== BUG: KASAN: use-after-free in tipc_bcast_get_mode+0x3ab/0x400 net/tipc/bcast.c:759 Read of size 1 at addr ffff88805e6b3571 by task kworker/0:6/3850 CPU: 0 PID: 3850 Comm: kworker/0:6 Not tainted 5.8.0-rc7-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events tipc_net_finalize_work Thread 1's call trace: [...] kfree+0x103/0x2c0 mm/slab.c:3757 <- bcbase releasing tipc_bcast_stop+0x1b0/0x2f0 net/tipc/bcast.c:721 tipc_exit_net+0x24/0x270 net/tipc/core.c:112 [...] Thread 2's call trace: [...] tipc_bcast_get_mode+0x3ab/0x400 net/tipc/bcast.c:759 <- bcbase has already been freed by Thread 1 tipc_node_broadcast+0x9e/0xcc0 net/tipc/node.c:1744 tipc_nametbl_publish+0x60b/0x970 net/tipc/name_table.c:752 tipc_net_finalize net/tipc/net.c:141 [inline] tipc_net_finalize+0x1fa/0x310 net/tipc/net.c:131 tipc_net_finalize_work+0x55/0x80 net/tipc/net.c:150 [...] ================================================================== BUG: KASAN: use-after-free in tipc_named_reinit+0xef/0x290 net/tipc/name_distr.c:344 Read of size 8 at addr ffff888052ab2000 by task kworker/0:13/30628 CPU: 0 PID: 30628 Comm: kworker/0:13 Not tainted 5.8.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events tipc_net_finalize_work Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1f0/0x31e lib/dump_stack.c:118 print_address_description+0x66/0x5a0 mm/kasan/report.c:383 __kasan_report mm/kasan/report.c:513 [inline] kasan_report+0x132/0x1d0 mm/kasan/report.c:530 tipc_named_reinit+0xef/0x290 net/tipc/name_distr.c:344 tipc_net_finalize+0x85/0xe0 net/tipc/net.c:138 tipc_net_finalize_work+0x50/0x70 net/tipc/net.c:150 process_one_work+0x789/0xfc0 kernel/workqueue.c:2269 worker_thread+0xaa4/0x1460 kernel/workqueue.c:2415 kthread+0x37e/0x3a0 drivers/block/aoe/aoecmd.c:1234 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293 [...] Freed by task 14058: save_stack mm/kasan/common.c:48 [inline] set_track mm/kasan/common.c:56 [inline] kasan_set_free_info mm/kasan/common.c:316 [inline] __kasan_slab_free+0x114/0x170 mm/kasan/common.c:455 __cache_free mm/slab.c:3426 [inline] kfree+0x10a/0x220 mm/slab.c:3757 tipc_exit_net+0x29/0x50 net/tipc/core.c:113 ops_exit_list net/core/net_namespace.c:186 [inline] cleanup_net+0x708/0xba0 net/core/net_namespace.c:603 process_one_work+0x789/0xfc0 kernel/workqueue.c:2269 worker_thread+0xaa4/0x1460 kernel/workqueue.c:2415 kthread+0x37e/0x3a0 drivers/block/aoe/aoecmd.c:1234 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293 Solution 1 (preferer): Fix it by calling flush_scheduled_work() to make sure the tipc_net_finalize_work() stopped before releasing bcbase object. Solution 2: Fix it by introducing a bit flag and returning if flag is zero (object had already been freed) Reported-by: syzbot+6ea1f7a8df64596ef...@syzkaller.appspotmail.com Reported-by: syzbot+e9cc557752ab126c1...@syzkaller.appspotmail.com Signed-off-by: Hoang Huu Le <hoang.h...@dektech.com.au> --- net/tipc/bcast.c | 1 + net/tipc/core.c | 1 + net/tipc/core.h | 1 + net/tipc/net.c | 3 +++ 4 files changed, 6 insertions(+) diff --git a/net/tipc/bcast.c b/net/tipc/bcast.c index 940d176e0e87..56b624c8b6d4 100644 --- a/net/tipc/bcast.c +++ b/net/tipc/bcast.c @@ -718,6 +718,7 @@ void tipc_bcast_stop(struct net *net) struct tipc_net *tn = net_generic(net, tipc_net_id);synchronize_net();+ clear_bit_unlock(0, &tn->net_exit_flag); kfree(tn->bcbase); kfree(tn->bcl); } diff --git a/net/tipc/core.c b/net/tipc/core.c index 4f6dc74adf45..93ea7dc05bf2 100644 --- a/net/tipc/core.c +++ b/net/tipc/core.c @@ -60,6 +60,7 @@ static int __net_init tipc_init_net(struct net *net) tn->trial_addr = 0; tn->addr_trial_end = 0; tn->capabilities = TIPC_NODE_CAPABILITIES; + test_and_set_bit_lock(0, &tn->net_exit_flag); memset(tn->node_id, 0, sizeof(tn->node_id)); memset(tn->node_id_string, 0, sizeof(tn->node_id_string)); tn->mon_threshold = TIPC_DEF_MON_THRESHOLD; diff --git a/net/tipc/core.h b/net/tipc/core.h index 631d83c9705f..aa75882dd932 100644 --- a/net/tipc/core.h +++ b/net/tipc/core.h @@ -143,6 +143,7 @@ struct tipc_net { /* TX crypto handler */ struct tipc_crypto *crypto_tx; #endif + unsigned long net_exit_flag; };static inline struct tipc_net *tipc_net(struct net *net)diff --git a/net/tipc/net.c b/net/tipc/net.c index 85400e4242de..0dcbfcff5ad3 100644 --- a/net/tipc/net.c +++ b/net/tipc/net.c @@ -132,6 +132,9 @@ static void tipc_net_finalize(struct net *net, u32 addr) { struct tipc_net *tn = tipc_net(net);+ if (unlikely(!test_bit(0, &tn->net_exit_flag)))+ return; + if (cmpxchg(&tn->node_addr, 0, addr)) return; tipc_set_node_addr(net, addr);
This solution should not cause any deadlocks, I hope. Acked-by: Jon Maloy <jma...@redhat.com> _______________________________________________ tipc-discussion mailing list tipc-discussion@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/tipc-discussion
