From: Anton Volkov <avolkov@ispras.ru>
To: david.choi@micrel.com, davem@davemloft.net
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
ldv-project@linuxtesting.org,
Alexey Khoroshilov <khoroshilov@ispras.ru>
Subject: Possible race in ks8851_mll.ko
Date: Tue, 15 Aug 2017 18:57:32 +0300 [thread overview]
Message-ID: <49e80d06-531e-178e-1cb0-3293f275847f@ispras.ru> (raw)
Hello.
While searching for races in the Linux kernel I've come across
"drivers/net/ethernet/micrel/ks8851_mll.ko" module. Here is a question
that I came up with while analyzing results. Lines are given using the
info from Linux v4.12.
Consider the following case:
Thread 1: Thread 2:
ks8851_probe
ks = netdev_priv(netdev)
register_netdev
ks_start_xmit
->ks_soft_reset ->ks_tx_fifo_space
->ks_wrreg16 ->ks_rdreg16
ks->cmd_reg_cache = ... ks->cmd_reg_cache = ...
(ks8851_mll.c: line 536) (ks8851_mll.c: line 505)
iowrite16(ks->cmd_reg_cache) iowrite16(ks->cmd_reg_cache)
In this case early registration of netdev leads to callback interference
in the initialization process. Both ks_wrreg16() and ks_rdreg16() use
the same ks. If one of them changes the ks->cmd_reg_cache it is possible
that both will use the same value though it should be different. Is this
race feasible from your point of view?
Thank you for your time.
-- Anton Volkov
Linux Verification Center, ISPRAS
web: http://linuxtesting.org
e-mail: avolkov@ispras.ru
reply other threads:[~2017-08-15 15:57 UTC|newest]
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