[Buildroot] boot failure

[Giulio Benetti]

Hi,

Il 06/05/2018 10:32, Peter Korsgaard ha scritto:
>>>>>> "Enoch" == Enoch W <ixew at hotmail.com> writes:
> 
>   > Hi,
>   > Recent buildroot versions, updated from git master, start getting stuck with:
> 
>   > random: dropbear: uninitialized urandom read (32 bytes read)
> 
> This normally means that something (in this case dropbear) tries to get
> /dev/{,u}random data from the kernel very early.
> 
> What is your configuration / what have you customized related to
> dropbear? We by default run dropbear with the -R option to only generate
> the host keys on the first connection, so this shouldn't happen.
> 
> I can also not reproduce it here:
> 
> Initializing random number generator... done.
> Starting network: 8139cp 0000:00:0c.0 eth0: link up, 100Mbps, full-duplex, lpa 0x05E1
> udhcpc: started, v1.28.3
> udhcpc: sending discover
> udhcpc: sending select for 10.0.2.15
> udhcpc: lease of 10.0.2.15 obtained, lease time 86400
> deleting routers
> adding dns 10.0.2.3
> OK
> Starting dropbear sshd: OK
> 
> Welcome to Buildroot
> buildroot login:
> 
> 
> Looking closer, I do see that dropbear indeed tries to read 32 bytes
> from /dev/urandom at startup. I'm not sure if that is something new or
> if it has always been like that. You better ask on the dropbear mailing
> list (dropbear at ucc.asn.au) for more details:
> 
> # strace -e open,read,getrandom dropbear -R -F
> open("/lib//libc.so.0", O_RDONLY)       = 3
> read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0(\0\1\0\0\0 \343\0\0004\0\0\0"..., 4096) = 4096
> open("/etc/dropbear/dropbear_rsa_host_key", O_RDONLY|O_LARGEFILE) = -1 ENOENT (No such file or directory)
> open("/etc/dropbear/dropbear_dss_host_key", O_RDONLY|O_LARGEFILE) = -1 ENOENT (No such file or directory)
> open("/etc/dropbear/dropbear_ecdsa_host_key", O_RDONLY|O_LARGEFILE) = -1 ENOENT (No such file or directory)
> open("/dev/urandom", O_RDONLY|O_LARGEFILE) = 3
> read(3, "\35=\2109\343Z(\251\325\211F0o'*\206s\247\242\336\336\313\207\262\273W\260:j\32\370\270", 32) = 32
> 

I'm experimenting the same thing with udev, this is my log:
"
[    5.334345] udevd[83]: starting version 3.2.5 

[    5.352869] random: udevd: uninitialized urandom read (16 bytes read) 

[    5.380840] random: udevd: uninitialized urandom read (16 bytes read) 

[    5.387495] random: udevd: uninitialized urandom read (16 bytes read) 

[    5.468700] udevd[84]: starting eudev-3.2.5 

[    6.445387] urandom_read: 1 callbacks suppressed 

[    6.445397] random: dd: uninitialized urandom read (512 bytes read) 

[    6.561425] random: dbus-uuidgen: uninitialized urandom read (12 
bytes read)
[    6.68793 random: dbus-uuidgen: uninitialized urandom read (8 bytes 
read)
[    6.894495] random: crng init done 

[    6.897924] random: 2 urandom warning(s) missed due to ratelimiting
"

Since complains with dropbear with Enoch and udev with me,
it seems something kernel related, need to debug it.

Kind regards

-- 
Giulio Benetti
CTO

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