From: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
To: Dmitry Vyukov <dvyukov@google.com>, Mimi Zohar <zohar@linux.ibm.com>
Cc: syzbot <syzbot+a4a503d7f37292ae1664@syzkaller.appspotmail.com>,
Dmitry Kasatkin <dmitry.kasatkin@gmail.com>,
James Morris <jmorris@namei.org>,
linux-integrity@vger.kernel.org,
LKML <linux-kernel@vger.kernel.org>,
linux-security-module <linux-security-module@vger.kernel.org>,
"Serge E. Hallyn" <serge@hallyn.com>,
syzkaller-bugs <syzkaller-bugs@googlegroups.com>
Subject: Re: inconsistent lock state in ima_process_queued_keys
Date: Tue, 14 Jan 2020 09:19:06 -0800
Message-ID: <52f0bced-2d8b-bdf4-b65a-26689ea1aed1@linux.microsoft.com> (raw)
In-Reply-To: <CACT4Y+bgQVmibpeJgpwb_JTKW6jx3dzv0M-NGVat8qvJTo4X7A@mail.gmail.com>
Hi Dmitry,
> --- a/security/integrity/ima/ima_asymmetric_keys.c
> +++ b/security/integrity/ima/ima_asymmetric_keys.c
> @@ -103,17 +103,18 @@ static bool ima_queue_key(struct key *keyring,
> const void *payload,
> {
> bool queued = false;
> struct ima_key_entry *entry;
> + unsigned long flags;
>
> entry = ima_alloc_key_entry(keyring, payload, payload_len);
> if (!entry)
> return false;
>
> - spin_lock(&ima_keys_lock);
> + spin_lock_irqsave(&ima_keys_lock, flags);
> if (!ima_process_keys) {
> list_add_tail(&entry->list, &ima_keys);
> queued = true;
> }
> - spin_unlock(&ima_keys_lock);
> + spin_unlock_irqrestore(&ima_keys_lock, flags);
>
> if (!queued)
> ima_free_key_entry(entry);
>
Using sping_lock_irqsave() and spin_lock_irqrestore() in ima_queue_key()
is the right approach. Found a relevant blog below:
https://stackoverflow.com/questions/50637489/spin-lock-irqsave-in-interrupt-context
I think it would be safe to use the same spinlock functions in
ima_process_queued_keys() as well, but not a must.
Could you please confirm if your change fixed the crash?
I'll post a patch shortly.
thanks,
-lakshmi
next prev parent reply index
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-14 13:56 syzbot
2020-01-14 13:58 ` Dmitry Vyukov
2020-01-14 14:56 ` Mimi Zohar
2020-01-14 15:21 ` Dmitry Vyukov
2020-01-14 16:54 ` Lakshmi Ramasubramanian
2020-01-14 17:19 ` Lakshmi Ramasubramanian [this message]
2020-01-18 3:14 ` syzbot
2020-01-18 5:22 ` Lakshmi Ramasubramanian
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