On 17.05.2018 00:43 Ben Caradoc-Davies wrote:
On 16/05/18 19:28, w...@hllmnn.de wrote:
I just did a fresh install of testing with XFCE. After entering the
login
credentials the screen was black for 30-60 seconds before the desktop
environment showed up. Assuming a bug in XFCE, I performed another
fresh install
with MATE, but a similar effect occured: after login the background
image is
shown for 30-60 seconds before the desktop is fully loaded.
What happens if you wiggle your mouse or provide keyboard activity
while waiting? For example, if you wiggle your mouse vigorously for
two seconds or press the Alt key 20 times? Does the wait end sooner?
In Linux 4.16, the getrandom system call (without the GRND_NONBLOCK
flag) blocks until sufficient entropy is available in the pool. This
is the documented behaviour, and Linux 4.16 now enforces it to fix
CVE-2018-1108. This has caught out several services that try to use
getrandom (without the GRND_NONBLOCK flag) at early boot, including
plymouth (via fontconfig) and gdm3. What you see might have the same
cause. For details of my investigation, see:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=897572
Wiggling your mouse or providing keyboard activity adds entropy to the
pool. If this reduces the waiting time, you might be affected by the
same bug.
Kind regards,
Hi Ben,
Yes, you're right! When I wiggle the mouse the wait ends sooner. Indeed,
if I don't move the mouse at all and don't press any key the screen just
stays blank (I waited approx. 5 minutes and it still was black).
I attached the output of dmesg | grep "random". As you can see, "crng
init done" appears after the 5 minutes I waited.
Since there is no "splash" in my kernel command line in grub, I added
"noplymouth" to it, but that didn't help. Maybe it's another package
that calls getrandom without GRND_NONBLOCK. Let me know if I can support
the investigation somehow.
Kind regards,
Dino
[ 0.000000] random: get_random_bytes called from start_kernel+0x94/0x478 with crng_init=0
[ 4.426793] random: fast init done
[ 5.305730] random: systemd: uninitialized urandom read (16 bytes read)
[ 5.306079] random: systemd: uninitialized urandom read (16 bytes read)
[ 5.309089] random: systemd: uninitialized urandom read (16 bytes read)
[ 5.309237] random: systemd: uninitialized urandom read (16 bytes read)
[ 5.309399] random: systemd: uninitialized urandom read (16 bytes read)
[ 5.309598] random: systemd: uninitialized urandom read (16 bytes read)
[ 5.309751] random: systemd: uninitialized urandom read (16 bytes read)
[ 5.309900] random: systemd: uninitialized urandom read (16 bytes read)
[ 5.310030] random: systemd: uninitialized urandom read (16 bytes read)
[ 5.310093] random: systemd: uninitialized urandom read (16 bytes read)
[ 313.172388] random: crng init done
