[PATCHv2] thunderbolt: do not double dequeue a request
From: Sergey Senozhatsky
Date: Thu Mar 27 2025 - 07:45:28 EST
Some of our devices crash in tb_cfg_request_dequeue():
general protection fault, probably for non-canonical address 0xdead000000000122
CPU: 6 PID: 91007 Comm: kworker/6:2 Tainted: G U W 6.6.65)
RIP: 0010:tb_cfg_request_dequeue+0x2d/0xa0
Call Trace:
<TASK>
? tb_cfg_request_dequeue+0x2d/0xa0
tb_cfg_request_work+0x33/0x80
worker_thread+0x386/0x8f0
kthread+0xed/0x110
ret_from_fork+0x38/0x50
ret_from_fork_asm+0x1b/0x30
The circumstances are unclear, however, the theory is that
tb_cfg_request_work() can be scheduled twice for a request:
first time via frame.callback from ring_work() and second
time from tb_cfg_request(). Both times kworkers will execute
tb_cfg_request_dequeue(), which results in double list_del()
from the ctl->request_queue (the list poison deference hints
at it: 0xdead000000000122).
Another possibility can be tb_cfg_request_sync():
tb_cfg_request_sync()
tb_cfg_request()
schedule_work(&req->work) -> tb_cfg_request_dequeue()
tb_cfg_request_cancel()
schedule_work(&req->work) -> tb_cfg_request_dequeue()
To address the issue, do not dequeue requests that don't
have TB_CFG_REQUEST_ACTIVE bit set.
Signed-off-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
v2: updated commit message, kept list_del()
drivers/thunderbolt/ctl.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/thunderbolt/ctl.c b/drivers/thunderbolt/ctl.c
index cd15e84c47f4..1db2e951b53f 100644
--- a/drivers/thunderbolt/ctl.c
+++ b/drivers/thunderbolt/ctl.c
@@ -151,6 +151,11 @@ static void tb_cfg_request_dequeue(struct tb_cfg_request *req)
struct tb_ctl *ctl = req->ctl;
mutex_lock(&ctl->request_queue_lock);
+ if (!test_bit(TB_CFG_REQUEST_ACTIVE, &req->flags)) {
+ mutex_unlock(&ctl->request_queue_lock);
+ return;
+ }
+
list_del(&req->list);
clear_bit(TB_CFG_REQUEST_ACTIVE, &req->flags);
if (test_bit(TB_CFG_REQUEST_CANCELED, &req->flags))
--
2.49.0.395.g12beb8f557-goog