Re: file offset corruption on 32-bit machines?

From: Alexey Dobriyan
Date: Mon Apr 14 2008 - 14:39:22 EST


On Mon, Apr 14, 2008 at 05:54:52PM +0100, Alan Cox wrote:
> > Well, but imagine you have a file /proc/my_secret_file from which you
> > are able to read from position A:a and B:b but not from position
> > A:b. Concievably, checks for the file position could be bypassed because of
> > this race... I know this is kind of dumb example but I can imagine someone
>
> Unlikely as the ppos passed to the driver is a private copy and the user
> could equally use pread/pwrite to specify that offset.

pread is banned on proc files implemented via seq_files.
And in no-seq_file case, there are MAX_NON_LFS checks which fits into
32 bits.

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