From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752109AbdBIXN6 (ORCPT ); Thu, 9 Feb 2017 18:13:58 -0500 Received: from mail-pg0-f44.google.com ([74.125.83.44]:33149 "EHLO mail-pg0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751457AbdBIXN4 (ORCPT ); Thu, 9 Feb 2017 18:13:56 -0500 Date: Thu, 9 Feb 2017 15:04:00 -0800 From: Brian Norris To: Kees Cook Cc: Anton Vorontsov , Colin Cross , Tony Luck , LKML , Joel Fernandes , Guenter Roeck Subject: [PATCH] pstore: unconditionally initialize spinlock and flags Message-ID: <20170209230359.GA111957@google.com> References: <20170209064444.23274-1-briannorris@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org We check to see if a buffer is already sane-looking, and if it's sane, we don't wipe it. But that's not an excuse to avoid initializing our spinlocks or setting our flags. Without this, we might see spinlock debugging messages like this at boot: [ 0.760836] persistent_ram: found existing buffer, size 29988, start 29988 [ 0.765112] persistent_ram: found existing buffer, size 30105, start 30105 [ 0.769435] persistent_ram: found existing buffer, size 118542, start 118542 [ 0.785960] persistent_ram: found existing buffer, size 0, start 0 [ 0.786098] persistent_ram: found existing buffer, size 0, start 0 [ 0.786131] pstore: using zlib compression [ 0.790716] BUG: spinlock bad magic on CPU#0, swapper/0/1 [ 0.790729] lock: 0xffffffc0d1ca9bb0, .magic: 00000000, .owner: /-1, .owner_cpu: 0 [ 0.790742] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.10.0-rc2+ #913 [ 0.790747] Hardware name: Google Kevin (DT) [ 0.790750] Call trace: [ 0.790768] [] dump_backtrace+0x0/0x2bc [ 0.790780] [] show_stack+0x20/0x28 [ 0.790794] [] dump_stack+0xa4/0xcc [ 0.790809] [] spin_dump+0xe0/0xf0 [ 0.790821] [] spin_bug+0x30/0x3c [ 0.790834] [] do_raw_spin_lock+0x50/0x1b8 [ 0.790846] [] _raw_spin_lock_irqsave+0x54/0x6c [ 0.790862] [] buffer_size_add+0x48/0xcc [ 0.790875] [] persistent_ram_write+0x60/0x11c [ 0.790888] [] ramoops_pstore_write_buf+0xd4/0x2a4 [ 0.790900] [] pstore_console_write+0xf0/0x134 [ 0.790912] [] console_unlock+0x48c/0x5e8 [ 0.790923] [] register_console+0x3b0/0x4d4 [ 0.790935] [] pstore_register+0x1a8/0x234 [ 0.790947] [] ramoops_probe+0x6b8/0x7d4 [ 0.790961] [] platform_drv_probe+0x7c/0xd0 [ 0.790972] [] driver_probe_device+0x1b4/0x3bc [ 0.790982] [] __device_attach_driver+0xc8/0xf4 [ 0.790996] [] bus_for_each_drv+0xb4/0xe4 [ 0.791006] [] __device_attach+0xd0/0x158 [ 0.791016] [] device_initial_probe+0x24/0x30 [ 0.791026] [] bus_probe_device+0x50/0xe4 [ 0.791038] [] device_add+0x3a4/0x76c [ 0.791051] [] of_device_add+0x74/0x84 [ 0.791062] [] of_platform_device_create_pdata+0xc0/0x100 [ 0.791073] [] of_platform_device_create+0x34/0x40 [ 0.791086] [] of_platform_default_populate_init+0x58/0x78 [ 0.791097] [] do_one_initcall+0x88/0x160 [ 0.791109] [] kernel_init_freeable+0x264/0x31c [ 0.791123] [] kernel_init+0x18/0x11c [ 0.791133] [] ret_from_fork+0x10/0x50 [ 0.793717] console [pstore-1] enabled [ 0.797845] pstore: Registered ramoops as persistent store backend [ 0.804647] ramoops: attached 0x100000@0xf7edc000, ecc: 0/0 Fixes: 663deb47880f ("pstore: Allow prz to control need for locking") Fixes: 109704492ef6 ("pstore: Make spinlock per zone instead of global") Signed-off-by: Brian Norris --- > > Sorry for the late notice, but I just booted 4.10 on a Chromebook. This also > > may not be the "perfect" fix, but it's what I scrounged up in 5 minutes today. > > Eek! Thank you for catching this. I'll send to Linus for -rc8 (or > final?). If it's too late we'll get it in via -stable. Sorry, there's one more regression... This might be relatively harmless, since a 0-initialized spinlock is probably OK? fs/pstore/ram_core.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c index a857338b7dab..db5a32e5080e 100644 --- a/fs/pstore/ram_core.c +++ b/fs/pstore/ram_core.c @@ -478,6 +478,9 @@ static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig, sig ^= PERSISTENT_RAM_SIG; + prz->buffer_lock = __RAW_SPIN_LOCK_UNLOCKED(buffer_lock); + prz->flags = flags; + if (prz->buffer->sig == sig) { if (buffer_size(prz) > prz->buffer_size || buffer_start(prz) > buffer_size(prz)) @@ -496,8 +499,6 @@ static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig, prz->buffer->sig = sig; persistent_ram_zap(prz); - prz->buffer_lock = __RAW_SPIN_LOCK_UNLOCKED(buffer_lock); - prz->flags = flags; return 0; } -- 2.11.0.483