bisecting fixing commit since ba4f184e126b751d1bffad5897f263108befc780
building syzkaller on 9e1fa68ee1625a7f0ef03906ee1abb40cb987fbf
testing commit ba4f184e126b751d1bffad5897f263108befc780 with gcc (GCC) 8.1.0
kernel signature: eb04680aa5867ff3ef698af0c9dc4e62568457a997f4b0c925e1129fde0bbd24
all runs: crashed: WARNING: refcount bug in qrtr_node_lookup
testing current HEAD 4ef8451b332662d004df269d4cdeb7d9f31419b5
testing commit 4ef8451b332662d004df269d4cdeb7d9f31419b5 with gcc (GCC) 8.1.0
kernel signature: 33044193a00599e364d3643401b05f42dbe8d417f51d1cfb4f796e57826b487e
all runs: crashed: WARNING: refcount bug in qrtr_node_lookup
revisions tested: 2, total time: 24m32.493145871s (build: 10m23.001947143s, test: 13m30.393327101s)
the crash still happens on HEAD
commit msg: Merge tag 'perf-tools-for-v5.10-2020-11-03' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux
crash: WARNING: refcount bug in qrtr_node_lookup
------------[ cut here ]------------
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 1 PID: 45 at lib/refcount.c:25 refcount_warn_saturate+0x80/0xe0 lib/refcount.c:25
Modules linked in:
CPU: 1 PID: 45 Comm: kworker/u4:3 Not tainted 5.10.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: qrtr_ns_handler qrtr_ns_worker
RIP: 0010:refcount_warn_saturate+0x80/0xe0 lib/refcount.c:25
Code: 05 ec 17 e9 02 01 e8 82 89 3e 01 0f 0b c3 80 3d dc 17 e9 02 00 75 b8 48 c7 c7 d0 28 19 84 c6 05 cc 17 e9 02 01 e8 63 89 3e 01 <0f> 0b c3 80 3d bf 17 e9 02 00 75 99 48 c7 c7 a8 28 19 84 c6 05 af
RSP: 0018:ffffc90000dd7ce0 EFLAGS: 00010082
RAX: 0000000000000000 RBX: ffff88811f048c00 RCX: 0000000000000002
RDX: 0000000080000002 RSI: ffffffff8429d4ae RDI: 00000000ffffffff
RBP: 0000000000000282 R08: 0000000000000000 R09: c0000000ffffdfff
R10: ffffc90000dd7b10 R11: ffffc90000dd7b08 R12: ffffc90000dd7dc0
R13: ffffc90000dd7d84 R14: 0000000000001000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88813bd00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000052cd18 CR3: 00000001090a1000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __refcount_add include/linux/refcount.h:199 [inline]
 __refcount_inc include/linux/refcount.h:250 [inline]
 refcount_inc include/linux/refcount.h:267 [inline]
 kref_get include/linux/kref.h:45 [inline]
 qrtr_node_acquire net/qrtr/qrtr.c:196 [inline]
 qrtr_node_lookup+0x67/0x80 net/qrtr/qrtr.c:389
 qrtr_send_resume_tx net/qrtr/qrtr.c:981 [inline]
 qrtr_recvmsg+0x134/0x1c0 net/qrtr/qrtr.c:1044
 qrtr_ns_worker+0xb2/0x960 net/qrtr/ns.c:692
 process_one_work+0x273/0x600 kernel/workqueue.c:2272
 worker_thread+0x38/0x380 kernel/workqueue.c:2418
 kthread+0x145/0x170 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296