From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:36666 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933639AbeAKOWZ (ORCPT ); Thu, 11 Jan 2018 09:22:25 -0500 Subject: Patch "hwrng: core - sleep interruptible in read" has been added to the 4.4-stable tree To: jslaby@suse.cz, gregkh@linuxfoundation.org, herbert@gondor.apana.org.au, linux-crypto@vger.kernel.org, mpm@selenic.com Cc: , From: Date: Thu, 11 Jan 2018 15:22:20 +0100 Message-ID: <1515680540980@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled hwrng: core - sleep interruptible in read to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: hwrng-core-sleep-interruptible-in-read.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From 1ab87298cb59b649d8d648d25dc15b36ab865f5a Mon Sep 17 00:00:00 2001 From: Jiri Slaby Date: Fri, 27 Nov 2015 16:50:43 +0100 Subject: hwrng: core - sleep interruptible in read From: Jiri Slaby 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 --- drivers/char/hw_random/core.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) --- a/drivers/char/hw_random/core.c +++ b/drivers/char/hw_random/core.c @@ -238,7 +238,10 @@ static ssize_t rng_dev_read(struct file goto out; } - mutex_lock(&reading_mutex); + if (mutex_lock_interruptible(&reading_mutex)) { + err = -ERESTARTSYS; + goto out_put; + } if (!data_avail) { bytes_read = rng_get_data(rng, rng_buffer, rng_buffer_size(), @@ -288,6 +291,7 @@ out: out_unlock_reading: mutex_unlock(&reading_mutex); +out_put: put_rng(rng); goto out; } Patches currently in stable-queue which might be from jslaby@suse.cz are queue-4.4/hwrng-core-sleep-interruptible-in-read.patch