linux-kernel - [BUG] net: e100: possible data races in e100

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Message-ID: <ecf9293b-9105-8eb1-7184-77de6dd77786@gmail.com>
Date:   Wed, 27 Jun 2018 09:30:51 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     jeffrey.t.kirsher@...el.com, jchapman@...alix.com
Cc:     intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [BUG] net: e100: possible data races in e100_watchdog()

The call paths in Linux 4.16.7 that may raise data races are:

CPU0:
e100_set_multicast_list
     e100_exec_cb
         line 879: spin_lock_irqsave()
         e100_configure
             line 1139: nic->flags [READ]
             line 1148: nic->flags [READ]

CPU1:
e100_watchdog:
     line 1758, 1756: nic->flags [WRITE]

The READ operations in CPU0 are performed with holding a spinlock (line 
879), but the WRITE operation in CPU1 is performed without holding this 
spinlock, so it may cause data races here.

A possible fix is to add spin_lock_irqsave() in e100_watchdog().
I am not sure that whether this possible fix is correct, so I only 
report the data races.

Best wishes,
Jia-Ju Bai