** Changed in: ccid (Ubuntu Xenial)
Status: Confirmed => In Progress
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https://bugs.launchpad.net/bugs/1551897
Title:
Excessive CPU utilization
Status in ccid package in Ubuntu:
Fix Released
Status in pcsc-lite package in Ubuntu:
Invalid
Status in ccid source package in Xenial:
In Progress
Status in pcsc-lite source package in Xenial:
Invalid
Status in pcsc-lite package in Debian:
Fix Released
Bug description:
[Impact]
When hotplugging a composite USB device that expose multiple
interfaces (such as a Yubikey NEO or Yubikey 4), libccid does not
correctly de-initialize the USB library when it skips over the non-
CCID interface.
This subsequently results in pcscd (or, presumably, anything that
loads libccid, though I don't think anything else does) either using
100% CPU or segfaulting when the device is unplugged.
This seems worthy of an SRU as it is an easily reproducible bug with a
simple, targeted fix.
[Test Case]
1. Make sure pcscd is running (sudo systemctl start pcscd; possibly sudo
systemctl restart pcscd if a potentially fixed package has just been installed)
2. Plug and then unplug a composite USB device that includes a CCID interface
(such as a Yubikey NEO)
3. Observe that pcscd has crashed with a segfault (sudo systemctl status
pcscd)
[Regression Potential]
The patch is quite narrow, and thus the potential for regression
should be limited. The new code adds calls to close_libusb_if_needed,
which is already written to be fairly conservative.
The worst case here is likely an unexpected call to libusb_exit, which
could cause libusb to get into an inconsistent state. However, in
practice the call seems quite safe, and the likelihood of regression
low.
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Original bug description:
In xenial, pcscd CPU utilization occasionally goes haywire:
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
27404 root 20 0 384264 4992 2228 S 100.3 0.0 75:39.03
/usr/sbin/pcscd --foreground --auto-exit
I get this about once a day since installing xenial. I can't quite
connect it to any specific event on the system, it just seems to
happen sporadically -- fan turns on, I run top, and there it is again.
Never had this issue on same hardware incl. smartcard with trusty.
I wonder if it might be this? https://bugs.debian.org/cgi-
bin/bugreport.cgi?bug=718473
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