Re: [PATCH 2.4] Fix rlimit check in precheck_file_write()

[Alan Cox]

On Mer, 2004-12-22 at 21:57, Jason Uhlenkott wrote:
> Remove a broken assumption that rlimits are 32 bits which can cause
> nasty things to happen on 64-bit machines if we try to write past the
> 2^32-1th character of a file and a larger file size limit exists.
> 
> Signed-off-by: Jason Uhlenkott <jasonuhl@xxxxxxx>
> 
> --- linux-2.4.29-pre3.orig/mm/filemap.c	2004-11-17 03:54:22.000000000 -0800
> +++ linux-2.4.29-pre3/mm/filemap.c	2004-12-22 13:41:46.000000000 -0800
> @@ -3088,9 +3088,9 @@
>  			send_sig(SIGXFSZ, current, 0);
>  			goto out;
>  		}
> -		if (pos > 0xFFFFFFFFULL || *count > limit - (u32)pos) {
> +		if (*count > limit - pos) {
>  			/* send_sig(SIGXFSZ, current, 0); */
> -			*count = limit - (u32)pos;
> +			*count = limit - pos;
>  		}

Are you sure this is safe for all conceivable 32bit cases as well as
your 64bit one ? I don't think it is looking at the overflow cases in
the if that you removed checking of.

Alan

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