Re: [PATCH V2] posix-timers: Protect posix clock array access against speculation

[Peter Zijlstra]

On Thu, Feb 15, 2018 at 05:21:55PM +0100, Thomas Gleixner wrote:
> The clockid argument of clockid_to_kclock() comes straight from user space
> via various syscalls and is used as index into the posix_clocks array.
> 
> Protect it against spectre v1 array out of bounds speculation. Remove the
> redundant check for !posix_clock[id] as this is another source for
> speculation and does not provide any advantage over the return
> posix_clock[id] path which returns NULL in that case anyway.
> 
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx

Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>

It might also be useful to figure out why the automation didn't flag
this one, its about as trivial as it gets.