On Tue 09-11-21 10:58:01, Geert Uytterhoeven wrote:
> 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.
Yeah, thanks for the heads up. I've noticed the warning from 0-day as well
and realized this is a real problem on 32-bit systems. UDF does support
dirs larger than 4G in principle (although practically anything larger than
say 1MB is probably unusable due to linear directory structure :). Anyway,
I'm working on a fix.
Honza
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
