bisecting fixing commit since 88d6de67e390b6093f2c11189ad022988a9e2961
building syzkaller on 56cd6c9b80ee424566e3ceaf8a4b042803a130ad
testing commit 88d6de67e390b6093f2c11189ad022988a9e2961 with gcc (GCC) 8.1.0
kernel signature: 02b5fd6604e9a82e3939e213c29bbb47a6a18a3c3699a8fcf51b67754ea93582
all runs: crashed: KASAN: null-ptr-deref Read in __tcf_idr_release
testing current HEAD 20b3a3dfdf6c55b50bbdc8e231a3dbf6bf965dc7
testing commit 20b3a3dfdf6c55b50bbdc8e231a3dbf6bf965dc7 with gcc (GCC) 8.1.0
kernel signature: 76228b3926e569bb396d1d6188d2699b13db0ebdf0bd791d7de00802a5d7ea7f
all runs: crashed: KASAN: null-ptr-deref Read in __tcf_idr_release
revisions tested: 2, total time: 25m46.649370212s (build: 18m9.571821938s, test: 6m11.155534738s)
the crash still happens on HEAD
commit msg: Linux 4.19.134
crash: KASAN: null-ptr-deref Read in __tcf_idr_release
IPv6: ADDRCONF(NETDEV_UP): batadv_slave_1: link is not ready
batman_adv: batadv0: Interface activated: batadv_slave_1
device veth0_vlan entered promiscuous mode
IPv6: ADDRCONF(NETDEV_UP): veth1_to_batadv: link is not ready
==================================================================
BUG: KASAN: null-ptr-deref in atomic_read include/asm-generic/atomic-instrumented.h:21 [inline]
BUG: KASAN: null-ptr-deref in __tcf_idr_release+0x30/0x90 net/sched/act_api.c:139
Read of size 4 at addr 0000000000000010 by task syz-executor.3/7767

CPU: 1 PID: 7767 Comm: syz-executor.3 Not tainted 4.19.134-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x123/0x177 lib/dump_stack.c:118
 kasan_report_error mm/kasan/report.c:352 [inline]
 kasan_report.cold.9+0x6d/0x309 mm/kasan/report.c:412
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
 kasan_check_read+0x11/0x20 mm/kasan/kasan.c:272
 atomic_read include/asm-generic/atomic-instrumented.h:21 [inline]
 __tcf_idr_release+0x30/0x90 net/sched/act_api.c:139
 tcf_del_walker net/sched/act_api.c:266 [inline]
 tcf_generic_walker+0x595/0x930 net/sched/act_api.c:292
 tcf_ife_walker+0x113/0x1d0 net/sched/act_ife.c:862
 tca_action_flush net/sched/act_api.c:1142 [inline]
 tca_action_gd+0xd27/0x1480 net/sched/act_api.c:1248
 tc_ctl_action+0x1fe/0x3c6 net/sched/act_api.c:1373
 rtnetlink_rcv_msg+0x34f/0x8f0 net/core/rtnetlink.c:4777
 netlink_rcv_skb+0x13e/0x3d0 net/netlink/af_netlink.c:2455
 rtnetlink_rcv+0x10/0x20 net/core/rtnetlink.c:4795
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x443/0x650 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x765/0xc40 net/netlink/af_netlink.c:1909
 sock_sendmsg_nosec net/socket.c:622 [inline]
 sock_sendmsg+0xb5/0xf0 net/socket.c:632
 ___sys_sendmsg+0x647/0x950 net/socket.c:2115
 __sys_sendmsg+0xd9/0x180 net/socket.c:2153
 __do_sys_sendmsg net/socket.c:2162 [inline]
 __se_sys_sendmsg net/socket.c:2160 [inline]
 __x64_sys_sendmsg+0x73/0xb0 net/socket.c:2160
 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45b3c9
Code: 2d b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 fb b5 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fc40edffc78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fc40ee006d4 RCX: 000000000045b3c9
RDX: 0000000000000000 RSI: 0000000020000300 RDI: 0000000000000003
RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000009c2 R14: 00000000004cb3b8 R15: 000000000075bfd4
==================================================================