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Subject: Re: [PATCH 3/3] kasan: don't assume percpu shadow allocations will
 succeed
To:     Daniel Axtens <dja@axtens.net>, kasan-dev@googlegroups.com,
        linux-mm@kvack.org, glider@google.com,
        linux-kernel@vger.kernel.org, dvyukov@google.com
Cc:     daniel@iogearbox.net, cai@lca.pw,
        syzbot+82e323920b78d54aaed5@syzkaller.appspotmail.com,
        syzbot+59b7daa4315e07a994f1@syzkaller.appspotmail.com,
        Andrew Morton <akpm@linux-foundation.org>
References: <20191205140407.1874-1-dja@axtens.net>
 <20191205140407.1874-3-dja@axtens.net>
From:   Andrey Ryabinin <aryabinin@virtuozzo.com>
Message-ID: <87172e8f-9698-0805-252f-55f68ee07862@virtuozzo.com>
Date:   Fri, 6 Dec 2019 19:24:31 +0300
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On 12/5/19 5:04 PM, Daniel Axtens wrote:
> syzkaller and the fault injector showed that I was wrong to assume
> that we could ignore percpu shadow allocation failures.
> 
> Handle failures properly. Merge all the allocated areas back into the free
> list and release the shadow, then clean up and return NULL. The shadow
> is released unconditionally, which relies upon the fact that the release
> function is able to tolerate pages not being present.
> 
> Also clean up shadows in the recovery path - currently they are not
> released, which leaks a bit of memory.
> 
> Fixes: 3c5c3cfb9ef4 ("kasan: support backing vmalloc space with real shadow memory")
> Reported-by: syzbot+82e323920b78d54aaed5@syzkaller.appspotmail.com
> Reported-by: syzbot+59b7daa4315e07a994f1@syzkaller.appspotmail.com
> Cc: Dmitry Vyukov <dvyukov@google.com>
> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
> Signed-off-by: Daniel Axtens <dja@axtens.net>
> ---

Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>