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Re: kernel/3711: arc4random in kernel init causes uninitialised use of timeout_add and panic w/ DIAGNOSTIC
sys/net80211 initialisation uses arc4random for setup of an IV for WEP.
Either this is a bad design (i.e. it assumes that there is safe strong
random that can be called from a device pci attach methods), or it's a good
design with flawed implementation (i.e. should be using random() rather than
arc4random()) or it's a good design with good implementation (i.e. it's a
bug that arc4random() panics).
What do you experts recommend I do ?
(a) is there a safe way to get good randomness during pci derived attached
methods, if so, how ?
(b) if not, then obviously I need to fix the driver, but you'd think that
the kernel was tighter and would panic in arc4random explictly rather than
implicit failure through a secondary fault (in timeout_add).
London W2 4PS
+44 77 6969 0248
From: Michael Shalayeff [mailto:firstname.lastname@example.org]
Sent: 14 March 2004 09:10
To: Matthew Gream
Cc: 'Ted Unangst'; email@example.com
Subject: Re: kernel/3711: arc4random in kernel init causes uninitialised use
of timeout_add and panic w/ DIAGNOSTIC
Making, drinking tea and reading an opus magnum from Matthew Gream:
> I ported a driver from netbsd that did this; is there a more
> acceptable way to obtain random() data in methods called from pci attach ?
why do you need strong random there that early anyway?
> -----Original Message-----
> From: Ted Unangst [mailto:firstname.lastname@example.org]
> Sent: 13 March 2004 19:39
> To: Matthew
> Cc: email@example.com
> Subject: Re: kernel/3711: arc4random in kernel init causes
> uninitialised use of timeout_add and panic w/ DIAGNOSTIC
> On Sat, 13 Mar 2004, Matthew wrote:
> > Using arc4random before randomattach, e.g. from a PCI
> > attach,
> results in arc4maybeinit being
> > called with arc4random_initialized not set, resulting in
> > timeout_add
> on uninitialised
> > arc4_timeout, which panics in DIAGNOSTIC. Found in 3.3, but still
> present in HEAD.
> > >How-To-Repeat:
> > choose good pci_attach and use arc4random from dev/rndvar.h
> > &
> > build DIAGNOSTIC kernel
> > reboot and get nice panic from kern_timeout.c:163.
> why are you doing this?
> desire is not an occupation
paranoic mickey (my employers have changed but, the name has