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From: Konstantin Kharlamov <hi-angel@yandex.ru>
To: LVM general discussion and development <linux-lvm@redhat.com>
Subject: Re: [linux-lvm] Frequent crashes when accessing dev_name(dev) on an empty list
Date: Fri, 01 Apr 2022 17:48:28 +0300	[thread overview]
Message-ID: <a7140ff0ce32368c3d630dfc79474bb05b4f4e47.camel@yandex.ru> (raw)
In-Reply-To: <3e96860d112e86ee55fba0e5fffbf1ee433905e6.camel@yandex.ru>

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?
> 
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com
> https://listman.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
> 

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      parent reply	other threads:[~2022-04-01 14:55 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-21 13:45 Konstantin Kharlamov
2022-02-21 16:49 ` David Teigland
2022-02-21 17:35   ` Konstantin Kharlamov
2022-04-01 14:48 ` Konstantin Kharlamov [this message]

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