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SubjectPossible race in nsc-ircc.ko
Date
Hello.

While searching for races in the Linux kernel I've come across
"drivers/net/irda/nsc-ircc.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:
nsc_ircc_init
->nsc_ircc_open
self = netdev_priv(dev)
register_netdev(dev)
nsc_ircc_net_ioctl
->nsc_ircc_change_speed
self->dongle_id = ... <READ self->io.dongle_id>
(nsc-ircc.c: line 485) (nsc-ircc.c: line 1318)
platform_device_register_simple

Before the initialization of self->dongle_id in msc_ircc_open() its
value is 0. Thus if read access to its value in nsc_ircc_change_speed
occurs before the initialization there will be an attempt to change
speed of dongle with undesired id (if the dongle with id 0 exists). Is
this case 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

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