The syzbot fuzzer found that the interrupt-URB completion callback in
the cdc-wdm driver was taking too long, and the driver's immediate
resubmission of interrupt URBs with -EPROTO status combined with the
dummy-hcd emulation to cause a CPU lockup:
cdc_wdm 1-1:1.0: nonzero urb status received: -71
cdc_wdm 1-1:1.0: wdm_int_callback - 0 bytes
watchdog: BUG: soft lockup - CPU#0 stuck for 26s! [syz-executor782:6625]
CPU#0 Utilization every 4s during lockup:
#1: 98% system, 0% softirq, 3% hardirq, 0% idle
#2: 98% system, 0% softirq, 3% hardirq, 0% idle
#3: 98% system, 0% softirq, 3% hardirq, 0% idle
#4: 98% system, 0% softirq, 3% hardirq, 0% idle
#5: 98% system, 1% softirq, 3% hardirq, 0% idle
Modules linked in:
irq event stamp: 73096
hardirqs last enabled at (73095): [<ffff80008037bc00>] console_emit_next_record kernel/printk/printk.c:2935 [inline]
hardirqs last enabled at (73095): [<ffff80008037bc00>] console_flush_all+0x650/0xb74 kernel/printk/printk.c:2994
hardirqs last disabled at (73096): [<ffff80008af10b00>] __el1_irq arch/arm64/kernel/entry-common.c:533 [inline]
hardirqs last disabled at (73096): [<ffff80008af10b00>] el1_interrupt+0x24/0x68 arch/arm64/kernel/entry-common.c:551
softirqs last enabled at (73048): [<ffff8000801ea530>] softirq_handle_end kernel/softirq.c:400 [inline]
softirqs last enabled at (73048): [<ffff8000801ea530>] handle_softirqs+0xa60/0xc34 kernel/softirq.c:582
softirqs last disabled at (73043): [<ffff800080020de8>] __do_softirq+0x14/0x20 kernel/softirq.c:588
CPU: 0 PID: 6625 Comm: syz-executor782 Tainted: G W 6.10.0-rc2-syzkaller-g8867bbd4a056 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
Testing showed that the problem did not occur if the two error
messages -- the first two lines above -- were removed; apparently adding
material to the kernel log takes a surprisingly large amount of time.
In any case, the best approach for preventing these lockups and to
avoid spamming the log with thousands of error messages per second is
to ratelimit the two dev_err() calls. Therefore we replace them with
dev_err_ratelimited().
Signed-off-by: Alan Stern <[email protected]>
Suggested-by: Greg KH <[email protected]>
Reported-and-tested-by: [email protected]
Closes: https://lore.kernel.org/linux-usb/[email protected]/
Reported-and-tested-by: [email protected]
Closes: https://lore.kernel.org/linux-usb/[email protected]/
Fixes: 9908a32e94de ("USB: remove err() macro from usb class drivers")
Link: https://lore.kernel.org/linux-usb/[email protected]/
Cc: [email protected]
---
drivers/usb/class/cdc-wdm.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
Index: usb-devel/drivers/usb/class/cdc-wdm.c
===================================================================
--- usb-devel.orig/drivers/usb/class/cdc-wdm.c
+++ usb-devel/drivers/usb/class/cdc-wdm.c
@@ -266,14 +266,14 @@ static void wdm_int_callback(struct urb
dev_err(&desc->intf->dev, "Stall on int endpoint\n");
goto sw; /* halt is cleared in work */
default:
- dev_err(&desc->intf->dev,
+ dev_err_ratelimited(&desc->intf->dev,
"nonzero urb status received: %d\n", status);
break;
}
}
if (urb->actual_length < sizeof(struct usb_cdc_notification)) {
- dev_err(&desc->intf->dev, "wdm_int_callback - %d bytes\n",
+ dev_err_ratelimited(&desc->intf->dev, "wdm_int_callback - %d bytes\n",
urb->actual_length);
goto exit;
}
This is automated email and please do not reply to this email!
Dear submitter,
Thank you for submitting the patches to the linux bluetooth mailing list.
This is a CI test results with your patch series:
PW Link:https://patchwork.kernel.org/project/bluetooth/list/?series=861868
---Test result---
Test Summary:
CheckPatch FAIL 0.86 seconds
GitLint FAIL 0.47 seconds
SubjectPrefix FAIL 0.33 seconds
BuildKernel PASS 30.26 seconds
CheckAllWarning PASS 32.87 seconds
CheckSparse PASS 38.68 seconds
CheckSmatch PASS 104.83 seconds
BuildKernel32 PASS 29.43 seconds
TestRunnerSetup PASS 532.86 seconds
TestRunner_l2cap-tester PASS 20.45 seconds
TestRunner_iso-tester PASS 32.76 seconds
TestRunner_bnep-tester PASS 4.87 seconds
TestRunner_mgmt-tester FAIL 113.51 seconds
TestRunner_rfcomm-tester PASS 7.43 seconds
TestRunner_sco-tester PASS 13.04 seconds
TestRunner_ioctl-tester PASS 7.91 seconds
TestRunner_mesh-tester PASS 6.00 seconds
TestRunner_smp-tester PASS 6.99 seconds
TestRunner_userchan-tester PASS 5.07 seconds
IncrementalBuild PASS 28.37 seconds
Details
##############################
Test: CheckPatch - FAIL
Desc: Run checkpatch.pl script
Output:
USB: class: cdc-wdm: Fix CPU lockup caused by excessive log messages
WARNING: Prefer a maximum 75 chars per line (possible unwrapped commit description?)
#66:
hardirqs last enabled at (73095): [<ffff80008037bc00>] console_emit_next_record kernel/printk/printk.c:2935 [inline]
WARNING: Possible repeated word: 'Google'
#74:
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
WARNING: Prefer using '"%s...", __func__' to using 'wdm_int_callback', this function's name, in a string
#117: FILE: drivers/usb/class/cdc-wdm.c:276:
+ dev_err_ratelimited(&desc->intf->dev, "wdm_int_callback - %d bytes\n",
total: 0 errors, 3 warnings, 16 lines checked
NOTE: For some of the reported defects, checkpatch may be able to
mechanically convert to the typical style using --fix or --fix-inplace.
/github/workspace/src/src/13697702.patch has style problems, please review.
NOTE: Ignored message types: UNKNOWN_COMMIT_ID
NOTE: If any of the errors are false positives, please report
them to the maintainer, see CHECKPATCH in MAINTAINERS.
##############################
Test: GitLint - FAIL
Desc: Run gitlint
Output:
USB: class: cdc-wdm: Fix CPU lockup caused by excessive log messages
WARNING: I3 - ignore-body-lines: gitlint will be switching from using Python regex 'match' (match beginning) to 'search' (match anywhere) semantics. Please review your ignore-body-lines.regex option accordingly. To remove this warning, set general.regex-style-search=True. More details: https://jorisroovers.github.io/gitlint/configuration/#regex-style-search
13: B3 Line contains hard tab characters (\t): " #1: 98% system, 0% softirq, 3% hardirq, 0% idle"
14: B3 Line contains hard tab characters (\t): " #2: 98% system, 0% softirq, 3% hardirq, 0% idle"
15: B3 Line contains hard tab characters (\t): " #3: 98% system, 0% softirq, 3% hardirq, 0% idle"
16: B3 Line contains hard tab characters (\t): " #4: 98% system, 0% softirq, 3% hardirq, 0% idle"
17: B3 Line contains hard tab characters (\t): " #5: 98% system, 1% softirq, 3% hardirq, 0% idle"
20: B1 Line exceeds max length (117>80): "hardirqs last enabled at (73095): [<ffff80008037bc00>] console_emit_next_record kernel/printk/printk.c:2935 [inline]"
21: B1 Line exceeds max length (113>80): "hardirqs last enabled at (73095): [<ffff80008037bc00>] console_flush_all+0x650/0xb74 kernel/printk/printk.c:2994"
22: B1 Line exceeds max length (111>80): "hardirqs last disabled at (73096): [<ffff80008af10b00>] __el1_irq arch/arm64/kernel/entry-common.c:533 [inline]"
23: B1 Line exceeds max length (116>80): "hardirqs last disabled at (73096): [<ffff80008af10b00>] el1_interrupt+0x24/0x68 arch/arm64/kernel/entry-common.c:551"
24: B1 Line exceeds max length (104>80): "softirqs last enabled at (73048): [<ffff8000801ea530>] softirq_handle_end kernel/softirq.c:400 [inline]"
25: B1 Line exceeds max length (104>80): "softirqs last enabled at (73048): [<ffff8000801ea530>] handle_softirqs+0xa60/0xc34 kernel/softirq.c:582"
26: B1 Line exceeds max length (99>80): "softirqs last disabled at (73043): [<ffff800080020de8>] __do_softirq+0x14/0x20 kernel/softirq.c:588"
27: B1 Line exceeds max length (105>80): "CPU: 0 PID: 6625 Comm: syz-executor782 Tainted: G W 6.10.0-rc2-syzkaller-g8867bbd4a056 #0"
28: B1 Line exceeds max length (89>80): "Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024"
43: B1 Line exceeds max length (82>80): "Closes: https://lore.kernel.org/linux-usb/[email protected]/"
45: B1 Line exceeds max length (82>80): "Closes: https://lore.kernel.org/linux-usb/[email protected]/"
46: B1 Line exceeds max length (97>80): "Link: https://lore.kernel.org/linux-usb/[email protected]/"
##############################
Test: SubjectPrefix - FAIL
Desc: Check subject contains "Bluetooth" prefix
Output:
"Bluetooth: " prefix is not specified in the subject
##############################
Test: TestRunner_mgmt-tester - FAIL
Desc: Run mgmt-tester with test-runner
Output:
Total: 492, Passed: 489 (99.4%), Failed: 1, Not Run: 2
Failed Test Cases
LL Privacy - Add Device 6 (RL is full) Failed 0.194 seconds
---
Regards,
Linux Bluetooth