Re: [PATCH] A new version of the sys_swapon bugfix

Jakub Jelinek (jj@sunsite.ms.mff.cuni.cz)
Tue, 3 Nov 1998 14:42:13 +0100 (MET)

>
> Jakub Jelinek <jj@sunsite.ms.mff.cuni.cz> writes:
>
> |> Hi!
> |>
> |> This is a new enhanced version of the sys_swapon bugfix.
> |> I've checked C standard and I cannot find any word about pointer + integer
> |> being promoted first to pointer + long,
>
> Pointer arithmetics is clearly defined, and you can add any integer type
> to a pointer, independent of the size of the pointer or integer.

I just made a typo in the comment above the code, it should really be
unsigned int i = 0;

which is the case in swapfile.c, where swap_header->info.nr_badpages is
unsigned int, thus if it is 0 and we subtract 1, it will result into
0xffffffff and &swap_header->info.badpages[0xffffffff] is really wrong on
64bit archs, so the patch is IMHO correct.

Cheers,
Jakub
___________________________________________________________________
Jakub Jelinek | jj@sunsite.mff.cuni.cz | http://sunsite.mff.cuni.cz
Administrator of SunSITE Czech Republic, MFF, Charles University
___________________________________________________________________
Ultralinux - first 64bit OS to take full power of the UltraSparc
Linux version 2.1.126 on a sparc64 machine (498.80 BogoMips).
___________________________________________________________________

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