From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x225PpNGqlHZYEto/T4U6qXH2RnwhTWQrsXuUJOufsyWk3MrdR1fEiT1nJuL+Am7smutAJkO6 ARC-Seal: i=1; a=rsa-sha256; t=1517591263; cv=none; d=google.com; s=arc-20160816; b=Z0ztSQbeUnhXHuqcFW2czptuy1I1ufyc6JgbgLV29BQZir4S7kfEQ5M+sY3fWYp+6e Ijg5VZMHSUxLhSNdhpjLXpYtOD8Qg0PfHpTbOTQVZvlU9ogoChpWmwhZ2yl6EkTZSR4k Zknc46T0fmKreFSf5TDbjP5wptUdrG2yMLdwsbqfY2tGgNKBt0UwGAMU04c+Ff/GLV3C innzCEz1G/HIyKTpAzgOR9HFFpnFgpsPIWQy8qGr62SnmtzEnJKyzK0ntEz4AW0KQ+U+ r/mH57uhU4ve6LdJeafKGNhXLq2hD/SDVUNKFHob7p73OGg/cr+jsqjW7HQJI8VhG8iX eZDg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=hj5zx4468mlMEZGgLuhuzW5aUqKjCst4c3T4gJTUb1Y=; b=k6dd8QXs9xy15df/0cxgMMOfWPNrLpVQOhmuiSPFWA+hCpU0PnjWpLQwLyZJE6Y9B2 MLFEb86vRb8OMke7Uv7znanLGj5Ir88TNodWETIt33prPx0tEPoqC/ysA9PWWoRp0YYX 6PFUbii/ZuvHDYKGsf+NepzTS9Iv5YnvsLEHtS5dqa2bLWLzVpW/10TEhDFW+maj4qP/ HH29ZQf/nyqMv3FNrsWxzpyDBCIQfOrdCSpDvP272eDU+KHTzlAIEJWcbBR65ez6W9Fk MLICdyvOYHnX8e5CfNBMDQqDwmt0haRsMNLJsWSAvMzt/+dAQS7/Y/S7Joe9bLTPkxyQ wWWQ== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.71.90 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.71.90 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, =?UTF-8?q?=E8=8C=83=E9=BE=99=E9=A3=9E?= , Linus Torvalds , Jens Axboe , Ben Hutchings Subject: [PATCH 4.14 002/156] loop: fix concurrent lo_open/lo_release Date: Fri, 2 Feb 2018 17:56:23 +0100 Message-Id: <20180202140840.355211867@linuxfoundation.org> X-Mailer: git-send-email 2.16.1 In-Reply-To: <20180202140840.242829545@linuxfoundation.org> References: <20180202140840.242829545@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1591309264145802026?= X-GMAIL-MSGID: =?utf-8?q?1591309776806326057?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Linus Torvalds commit ae6650163c66a7eff1acd6eb8b0f752dcfa8eba5 upstream. 范龙飞 reports that KASAN can report a use-after-free in __lock_acquire. The reason is due to insufficient serialization in lo_release(), which will continue to use the loop device even after it has decremented the lo_refcnt to zero. In the meantime, another process can come in, open the loop device again as it is being shut down. Confusion ensues. Reported-by: 范龙飞 Signed-off-by: Linus Torvalds Signed-off-by: Jens Axboe Cc: Ben Hutchings Signed-off-by: Greg Kroah-Hartman --- drivers/block/loop.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -1576,9 +1576,8 @@ out: return err; } -static void lo_release(struct gendisk *disk, fmode_t mode) +static void __lo_release(struct loop_device *lo) { - struct loop_device *lo = disk->private_data; int err; if (atomic_dec_return(&lo->lo_refcnt)) @@ -1605,6 +1604,13 @@ static void lo_release(struct gendisk *d mutex_unlock(&lo->lo_ctl_mutex); } +static void lo_release(struct gendisk *disk, fmode_t mode) +{ + mutex_lock(&loop_index_mutex); + __lo_release(disk->private_data); + mutex_unlock(&loop_index_mutex); +} + static const struct block_device_operations lo_fops = { .owner = THIS_MODULE, .open = lo_open,