On Mon, Aug 17, 2015 at 12:18:12PM +0300, Andrey Ryabinin wrote:
> This bug is similar to recently found bug in 9p:
> http://thread.gmane.org/gmane.linux.kernel/1931799/focus=1936542
Ow. For those who'd missed that fun: the bug in question had turned out to
be caused by improper reuse of request ids, _not_ in the call chain of
the triggering syscall.
> if (!retval) {
> struct iov_iter data = *iter;
> retval = mapping->a_ops->direct_IO(iocb, &data, pos);
> }
>
> if (retval > 0) {
> *ppos = pos + retval;
> iov_iter_advance(iter, retval);
>
>
> So either filemap_write_and_wait_range()
Shouldn't - it's supposed to return 0 or -E...
> or mapping->a_ops->direct_IO() returned more
> than 'count'.
Was there DAX involved? ->direct_IO() in there is blkdev_direct_IO(),
which takes rather different paths in those cases...
> > Also too the file and line number
> > (lib/iov_iter.c:511) are completely useless because of inlining,
> > though that's not kasan's fault.
Might make sense to slap
if (WARN_ON(size > iov_iter_count(i)))
print size and *i
and see if it triggers...
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