kernel/linux.git/drivers/char/hw_random/core.c, branch linux-4.4.y

hwrng: core - don't wait on add_early_randomness()

2019-10-05T10:27:55+00:00

commit 78887832e76541f77169a24ac238fccb51059b63 upstream. add_early_randomness() is called by hwrng_register() when the hardware is added. If this hardware and its module are present at boot, and if there is no data available the boot hangs until data are available and can't be interrupted. For instance, in the case of virtio-rng, in some cases the host can be not able to provide enough entropy for all the guests. We can have two easy ways to reproduce the problem but they rely on misconfiguration of the hypervisor or the egd daemon: - if virtio-rng device is configured to connect to the egd daemon of the host but when the virtio-rng driver asks for data the daemon is not connected, - if virtio-rng device is configured to connect to the egd daemon of the host but the egd daemon doesn't provide data. The guest kernel will hang at boot until the virtio-rng driver provides enough data. To avoid that, call rng_get_data() in non-blocking mode (wait=0) from add_early_randomness(). Signed-off-by: Laurent Vivier Fixes: d9e797261933 ("hwrng: add randomness to system from rng...") Cc: Reviewed-by: Theodore Ts'o Signed-off-by: Herbert Xu Signed-off-by: Greg Kroah-Hartman

hwrng: core - sleep interruptible in read

2018-01-17T08:35:28+00:00

commit 1ab87298cb59b649d8d648d25dc15b36ab865f5a upstream. hwrng kthread can be waiting via hwrng_fillfn for some data from a rng like virtio-rng: hwrng D ffff880093e17798 0 382 2 0x00000000 ... Call Trace: [] wait_for_completion_killable+0x96/0x210 [] virtio_read+0x57/0xf0 [virtio_rng] [] hwrng_fillfn+0x75/0x130 [] kthread+0xf3/0x110 And when some user program tries to read the /dev node in this state, we get: rngd D ffff880093e17798 0 762 1 0x00000004 ... Call Trace: [] mutex_lock_nested+0x15c/0x3e0 [] rng_dev_read+0x6e/0x240 [] __vfs_read+0x28/0xe0 [] vfs_read+0x83/0x130 And this is indeed unkillable. So use mutex_lock_interruptible instead of mutex_lock in rng_dev_read and exit immediatelly when interrupted. And possibly return already read data, if any (as POSIX allows). v2: use ERESTARTSYS instead of EINTR Signed-off-by: Jiri Slaby Cc: Matt Mackall Cc: Herbert Xu Cc: Signed-off-by: Herbert Xu Signed-off-by: Greg Kroah-Hartman

hwrng: core - Don't use a stack buffer in add_early_randomness()

2016-11-18T09:48:36+00:00

commit 6d4952d9d9d4dc2bb9c0255d95a09405a1e958f7 upstream. hw_random carefully avoids using a stack buffer except in add_early_randomness(). This causes a crash in virtio_rng if CONFIG_VMAP_STACK=y. Reported-by: Matt Mullins Tested-by: Matt Mullins Fixes: d3cc7996473a ("hwrng: fetch randomness only after device init") Signed-off-by: Andy Lutomirski Signed-off-by: Herbert Xu Signed-off-by: Greg Kroah-Hartman

hwrng: core - Simplify RNG switching from sysfs

2015-09-21T14:00:41+00:00

If we attempt to use sysfs to change the current RNG in the usual way i.e. issuing something like: `echo 8a8a000.rng > /sys/devices/virtual/misc/hw_random/rng_current` ... it will fail because the code doesn't currently take the '\n' into consideration. Well, now it does. Signed-off-by: Lee Jones Acked-by: Peter Korsgaard Signed-off-by: Herbert Xu

hwrng: core - correct error check of kthread_run call

2015-07-28T06:59:54+00:00

The kthread_run() function can return two different error values but the hwrng core only checks for -ENOMEM. If the other error value -EINTR is returned it is assigned to hwrng_fill and later used on a kthread_stop() call which naturally crashes. Cc: stable@vger.kernel.org Signed-off-by: Martin Schwidefsky Signed-off-by: Herbert Xu

Merge tag 'char-misc-4.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc

2015-04-21T16:42:58+00:00

Pull char/misc driver updates from Greg KH: "Here's the big char/misc driver patchset for 4.1-rc1. Lots of different driver subsystem updates here, nothing major, full details are in the shortlog. All of this has been in linux-next for a while" * tag 'char-misc-4.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (133 commits) mei: trace: remove unused TRACE_SYSTEM_STRING DTS: ARM: OMAP3-N900: Add lis3lv02d support Documentation: DT: lis302: update wakeup binding lis3lv02d: DT: add wakeup unit 2 and wakeup threshold lis3lv02d: DT: use s32 to support negative values Drivers: hv: hv_balloon: correctly handle num_pages>INT_MAX case Drivers: hv: hv_balloon: correctly handle val.freeram

hwrng: Avoid manual device_create_file() calls

2015-03-25T10:44:53+00:00

Use the new group field of struct miscdevice for managing the sysfs entries instead of manually adding/removing via device_create_file() and device_remove_file(). This simplifies the code a lot and fixes the possible races. Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman

hwrng: core - allow perfect entropy from hardware devices

2015-03-18T10:01:31+00:00

Hardware random number quality is measured from 0 (no entropy) to 1024 (perfect entropy). Allow hardware devices to assert the full range by truncating the device-provided value at 1024 instead of 1023. Signed-off-by: Keith Packard Signed-off-by: Herbert Xu

hwrng: add devm_* interfaces

2015-03-16T10:45:54+00:00

This change adds devm_hwrng_register and devm_hwrng_unregister which use can simplify error unwinding and unbinding code paths in device drivers. Signed-off-by: Dmitry Torokhov Signed-off-by: Herbert Xu

hwrng: core - Move hwrng_init call into set_current_rng

2014-12-25T21:33:36+00:00

We always do hwrng_init in set_current_rng. In fact, our current reference count system relies on this. So make this explicit by moving hwrng_init into set_current_rng. Signed-off-by: Herbert Xu