On Mon, 6 Aug 2018 12:22:03 +0200 Jan Kara <jack@xxxxxxx> wrote: > On Fri 20-07-18 16:14:29, Andrew Morton wrote: > > On Thu, 19 Jul 2018 10:58:12 +0200 Jan Kara <jack@xxxxxxx> wrote: > > > > > On Thu 19-07-18 16:17:26, Chengguang Xu wrote: > > > > When we try to truncate read count in generic_file_buffered_read(), > > > > should deliver (sb->s_maxbytes - offset) as maximum count not > > > > sb->s_maxbytes itself. > > > > > > > > Signed-off-by: Chengguang Xu <cgxu519@xxxxxxx> > > > > > > Looks good to me. You can add: > > > > > > Reviewed-by: Jan Kara <jack@xxxxxxx> > > > > Yup. > > > > What are the runtime effects of this bug? > > Good question. I think ->readpage() could be called for index beyond > maximum file size supported by the filesystem leading to weird filesystem > behavior due to overflows in internal calculations. > Sure. But is it possible for userspace to trigger this behaviour? Possibly all callers have already sanitized the arguments by this stage in which case the statement is arguably redundant. I guess I'll put a cc:stable on it and send it in for 4.19-rc1, so we get a bit more time to poke at it. But we should have a better understanding of the userspace impact.
