Re: Possible race in nsc-ircc.ko
On Fri, Aug 25, 2017 at 05:05:25PM +0300, Anton Volkov wrote: > 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 = ... 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 A first glance, that seems like a valid race. I'm not sure if there is a netdev lock/status to protect the driver, because it looks like doing any operation on a device before "open" has completed would be dangerous for most drivers. I don't have time to check the code paths, as I have not looked at that code in ages. Good luck ! Jean
Re: Possible race in nsc-ircc.ko
On Fri, Aug 25, 2017 at 05:05:25PM +0300, Anton Volkov wrote: > 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 = ... 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 A first glance, that seems like a valid race. I'm not sure if there is a netdev lock/status to protect the driver, because it looks like doing any operation on a device before "open" has completed would be dangerous for most drivers. I don't have time to check the code paths, as I have not looked at that code in ages. Good luck ! Jean
Possible race in nsc-ircc.ko
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 = ... 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: avol...@ispras.ru
Possible race in nsc-ircc.ko
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 = ... 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: avol...@ispras.ru
