From: Vladis Dronov <vdronov@redhat.com>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: linux-efi <linux-efi@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] efi: fix a race and a buffer overflow while reading efivars via sysfs
Date: Tue, 3 Mar 2020 05:24:58 -0500 (EST) [thread overview]
Message-ID: <358842423.12639861.1583231098544.JavaMail.zimbra@redhat.com> (raw)
In-Reply-To: <1980156503.12639063.1583230452485.JavaMail.zimbra@redhat.com>
Hello, Ard, all,
> > Wouldn't it be easier to pass a var_data_size stack variable into
> > efivar_entry_get(), and only update the value in 'var' if it is <=
> > 1024?
> >
>
> I was thinking about this approach, but this way we still do not protect
> var from a concurrent access. For example, efivar_data_read() can race
> with itself:
Oh, indeed, this race is not possible the way you sugget with a var_data_size
stack variable. Unfortunately, AFAIU, the read/write race stays:
> ... efivar read functions still can race with the write function
> efivar_store_raw(). Surely, the race window is much smaller but it is there.
> I strongly believe we need to protect all data accesses here with a lock.
Best regards,
Vladis Dronov | Red Hat, Inc. | The Core Kernel | Senior Software Engineer
next prev parent reply other threads:[~2020-03-03 10:25 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-03 8:55 [PATCH] efi: fix a race and a buffer overflow while reading efivars via sysfs Vladis Dronov
2020-03-03 9:15 ` Ard Biesheuvel
2020-03-03 10:14 ` Vladis Dronov
2020-03-03 10:20 ` Ard Biesheuvel
2020-03-03 10:24 ` Vladis Dronov [this message]
2020-03-04 6:51 ` joeyli
2020-03-04 15:45 ` Vladis Dronov
2020-03-04 15:47 ` Ard Biesheuvel
2020-03-04 15:49 ` [PATCH v2] " Vladis Dronov
2020-03-04 15:57 ` Ard Biesheuvel
2020-03-04 17:18 ` Vladis Dronov
2020-03-04 17:21 ` Ard Biesheuvel
2020-03-05 6:01 ` joeyli
2020-03-05 6:17 ` Vladis Dronov
2020-03-05 8:40 ` [PATCH v3 0/3] efi: fix a race and add a sanity check Vladis Dronov
2020-03-05 8:40 ` [PATCH v3 1/3] efi: fix a race and a buffer overflow while reading efivars via sysfs Vladis Dronov
2020-03-05 8:45 ` Ard Biesheuvel
2020-03-05 10:52 ` Vladis Dronov
2020-03-08 16:38 ` [tip: efi/urgent] efi: Fix " tip-bot2 for Vladis Dronov
2020-03-05 8:40 ` [PATCH v3 2/3] efi: add a sanity check to efivar_store_raw() Vladis Dronov
2020-03-08 16:38 ` [tip: efi/urgent] efi: Add " tip-bot2 for Vladis Dronov
2020-03-09 12:25 ` Sasha Levin
2020-03-09 12:38 ` Vladis Dronov
2020-03-16 14:21 ` Vladis Dronov
2020-03-05 8:40 ` [PATCH v3 3/3] efi: fix a mistype in comments mentioning efivar_entry_iter_begin() Vladis Dronov
2020-03-05 8:51 ` [PATCH v3 0/3] efi: fix a race and add a sanity check Ard Biesheuvel
2020-03-04 14:07 ` [PATCH] efi: fix a race and a buffer overflow while reading efivars via sysfs joeyli
2020-03-04 16:06 ` Vladis Dronov
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