Messages in this thread | | | Subject | Re: [PATCH] x86, random: Fix get_random_bytes() warning in x86 start_kernel | From | Prarit Bhargava <> | Date | Tue, 29 May 2018 12:58:10 -0400 |
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On 05/29/2018 12:07 PM, Theodore Y. Ts'o wrote: > On Tue, May 29, 2018 at 11:01:07AM -0400, Prarit Bhargava wrote: >> Kees, in early boot no pool is available so the stack canary is initialized from >> the TSC. Later in boot, the stack canary will use the the crng. >> >> ie) in early boot only TSC is okay, and late boot (when crng_ready() is true) >> the pool will be used. > > But that means all of the kernel threads (e.g., workqueues, et. al) > would not be well protected by the stack canary. That > seems.... rather unfortunate.
Well, as stated the TSC is used as a source of entropy in early boot. It's always been that way and get_random_bytes() AFAICT has always returned 0. CPUs added later on via hotplug do use get_random_bytes().
Does anyone cc'd have a better idea on how to get another source of entropy this early in boot?
P.
> > - Ted >
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