Re: linux-next: Tree for Nov 9

[Geert Uytterhoeven]

	Hi Jan,

As lore doesn't seem to have the original patch, I'm replying here.

On Tue, 9 Nov 2021, Stephen Rothwell wrote:
> Merging ext3/for_next (39a464de961f udf: Fix crash after seekdir)

noreply@xxxxxxxxxxxxxx reported for m68k/allmodconfig:
fs/udf/dir.c:78:18: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
fs/udf/dir.c:211:23: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]

The actual code does:

        * Did our position change since last readdir (likely lseek was
        * called)? We need to verify the position correctly points at the
        * beginning of some dir entry so that the directory parsing code does
        * not get confused. Since UDF does not have any reliable way of
        * identifying beginning of dir entry (names are under user control),
        * we need to scan the directory from the beginning.
        */
       if (ctx->pos != (loff_t)file->private_data) {
               emit_pos = nf_pos;
               nf_pos = 0;
       }

and:

       /* Store position where we've ended */
       file->private_data = (void *)ctx->pos;

Obviously this is not going to fly on 32-bit systems, as
file->private_data is 32-bit or 64-bit unsigned long, but ctx->pos is
always 64-bit loff_t.

I do not know if UDF supports files larger than 4 GiB (DVDs can be
larger).
If it doesn't, you need intermediate casts to uintptr_t.
If it does, you need a different solution.

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds