Re: [PATCH] fix compat console unimap regression

[David Miller <davem@davemloft.net>]

From: Hugh Dickins <hugh@veritas.com>
Date: Sat, 26 May 2007 00:39:17 +0100 (BST)

> Why is it that since the 2f1a2ccb9c0de632ab07193becf5f7121794f6ae console
> UTF-8 fixes went into 2.6.22-rc1, the PowerMac G5 shows only inverse video
> question marks for the text on tty2-6? whereas tty1 is fine, and so is x86.
> 
> No fault of that patch: by removing the old fallback behaviour, it reveals
> that 32-bit setfont running on 64-bit kernels has only really worked on
> the current console, the rest getting faked by that inadequate fallback.
> 
> Bring the compat do_unimap_ioctl into line with the main one: PIO_UNIMAP
> and GIO_UNIMAP apply to the specified tty, not redirected to fg_console.
> Use the same checks, and most particularly, remember to check access_ok:
> con_set_unimap and con_get_unimap are using __get_user and __put_user.
> 
> And the compat vt_check should ask for the same capability as the main
> one, CAP_SYS_TTY_CONFIG rather than CAP_SYS_ADMIN.  Added in vt_ioctl's
> vc_cons_allocated check for safety, though failure may well be impossible.
> 
> Signed-off-by: Hugh Dickins <hugh@veritas.com>

Thanks for figuring this out, I've been wondering what in the
world was causing this on sparc64.