[PATCH RFC v2] Input: yealink - abort URB submission on fatal errors

["syzbot" <syzbot@kernel.org>]

The yealink driver uses two URBs (interrupt and control) to communicate
with the device. When an URB completes with an error status (such as
-EPROTO), the completion handlers (urb_irq_callback and urb_ctl_callback)
log the error but do not abort. Instead, they proceed to process the
potentially invalid data and unconditionally resubmit the URB.

Because control URBs are not rate-limited by the USB core, resubmitting a
failing control URB in a tight loop floods the console with error messages
and keeps the CPU completely busy in the softirq context. This eventually
triggers an RCU preempt stall:

yealink 3-1:36.0: unexpected response 0
yealink 3-1:36.0: urb_ctl_callback - urb status -71
rcu: INFO: rcu_preempt self-detected stall on CPU
Call Trace:
 __console_flush_and_unlock kernel/printk/printk.c:3373 [inline]
 console_unlock+0xd1/0x1c0 kernel/printk/printk.c:3413
 dev_vprintk_emit+0x338/0x400 drivers/base/core.c:4996
 dev_printk_emit+0xee/0x140 drivers/base/core.c:5007
 usb_generic_driver_probe+0x10b/0x150 drivers/usb/core/generic.c:252
 ...
 hub_event+0x28e8/0x4d30 drivers/usb/core/hub.c:5953
 worker_thread+0x92d/0xe10 kernel/workqueue.c:3486
 kthread+0x388/0x470 kernel/kthread.c:436

Fix this by explicitly checking the URB status for fatal errors (-ENOENT,
-ECONNRESET, -ESHUTDOWN, -EPROTO, -EPIPE, -EILSEQ) in both
urb_irq_callback() and urb_ctl_callback(). If a fatal error is detected,
the callback now returns early, breaking the infinite resubmission loop and
preventing the RCU stall.

Fixes: aca951a22a1d ("[PATCH] input-driver-yealink-P1K-usb-phone")
Assisted-by: Gemini:gemini-3.8-flash syzbot
Reported-by: syzbot+78e2288f58b881ed3c45@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=78e2288f58b881ed3c45
Link: https://syzkaller.appspot.com/ai_job?id=479730c2-f271-451c-a31b-837d89cb018e
To: "Henk Vergonet" <Henk.Vergonet@gmail.com>
To: "Dmitry Torokhov" <dmitry.torokhov@gmail.com>
To: <linux-input@vger.kernel.org>
Cc: <linux-kernel@vger.kernel.org>

---
v2:
- Factored out fatal error checks into is_fatal_error() helper

v1:
https://lore.kernel.org/all/57cf484d-3235-473f-a61d-570585626176@mail.kernel.org/T/
---
diff --git a/drivers/input/misc/yealink.c b/drivers/input/misc/yealink.c
index 560f895a0..bf91f40cd 100644
--- a/drivers/input/misc/yealink.c
+++ b/drivers/input/misc/yealink.c
@@ -400,14 +400,32 @@ static int yealink_do_idle_tasks(struct yealink_dev *yld)
  * error,start
  *
  */
+static bool is_fatal_error(int status)
+{
+	switch (status) {
+	case -ENOENT:
+	case -ECONNRESET:
+	case -ESHUTDOWN:
+	case -EPROTO:
+	case -EPIPE:
+	case -EILSEQ:
+		return true;
+	default:
+		return false;
+	}
+}
+
 static void urb_irq_callback(struct urb *urb)
 {
 	struct yealink_dev *yld = urb->context;
 	int ret, status = urb->status;
 
-	if (status)
+	if (status) {
 		dev_err(&yld->intf->dev, "%s - urb status %d\n",
 			__func__, status);
+		if (is_fatal_error(status))
+			return;
+	}
 
 	switch (yld->irq_data->cmd) {
 	case CMD_KEYPRESS:
@@ -443,9 +461,12 @@ static void urb_ctl_callback(struct urb *urb)
 	struct yealink_dev *yld = urb->context;
 	int ret = 0, status = urb->status;
 
-	if (status)
+	if (status) {
 		dev_err(&yld->intf->dev, "%s - urb status %d\n",
 			__func__, status);
+		if (is_fatal_error(status))
+			return;
+	}
 
 	switch (yld->ctl_data->cmd) {
 	case CMD_KEYPRESS:


base-commit: 1590cf0329716306e948a8fc29f1d3ee87d3989f
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