Re: Frequent crashes when accessing dev_name(dev) on an empty list
Konstantin Kharlamov <[email protected]>
| Newsgroups | gmane.linux.lvm.general |
|---|---|
| Message-ID | <[email protected]> |
To close the topic: there was a discussion off-list, and a number of fixes were
merged. Some of them were tested by us as well (we backported them to older
LVM), and it's been more than a month since with no crashes. So the problem is
fixed.
On Mon, 2022-02-21 at 16:45 +0300, Konstantin Kharlamov wrote:
> Hello! We encountered quite a few of sporadic crashes, which upon inspection
> turned out to be caused by dev->aliases list being empty.
>
> One example of a fix (not tested):
>
> --- a/lib/label/hints.c
> +++ b/lib/label/hints.c
> @@ -471,7 +471,8 @@ int validate_hints(struct cmd_context *cmd, struct dm_list
> *hints)
> 471 if (!(iter = dev_iter_create(NULL, 0)))
> 472 return 0;
> 473 while ((dev = dev_iter_get(cmd, iter))) {
> 474 - if (!(hint = _find_hint_name(hints, dev_name(dev))))
> 474+ if (dm_list_empty(dev->aliases) ||
> 475+ !(hint = _find_hint_name(hints, dev_name(dev))))
> 475 476 continue;
> 476 477
> 477 478 /* The cmd hasn't needed this hint's dev so it's not
> been scanned. */
>
> So, what happened was that dev_name(dev) was extracting a `dev->aliases`
> element
> , however `dev->aliases` was empty, thus the extracted element was a junk.
>
> Although we encountered these crashes on an older 2.03.07 version, however the
> patch applies to latest master as well, thus the bugs are still relevant,
> which
> is odd. This makes me wondering, is this a known problem, could I possibly
> overlooked something, for example that dev->aliases should never be empty, and
> thus the fix just works around another problem? Any thoughts?
>
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>
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