Re: Potential information leak in save_xstate_epilog()

[Bae, Chang Seok]

On Nov 26, 2021, at 03:06, Alexander Potapenko <glider@xxxxxxxxxx> wrote:
> 
> Hi Chang, Thomas, Borislav,
> 
> "x86/fpu/signal: Prepare for variable sigframe length" has presumably
> introduced an information leak to the userspace.
> 
> According to https://elixir.bootlin.com/linux/v5.16-rc2/source/arch/x86/kernel/fpu/signal.c#L126,
> save_sw_bytes() only initializes the first 20 bytes of sw_bytes, but
> then the whole struct is copied to the userspace.

Looks like your fix was picked already though, thank you for catching this!

Thanks,
Chang