From: Greg KH <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org,
alan@lxorguk.ukuu.org.uk, Rabin Vincent <rabin@rab.in>,
Namjae Jeon <linkinjeon@gmail.com>,
Wu Fengguang <fengguang.wu@intel.com>
Subject: [08/15] writeback: fix dereferencing NULL bdi->dev on trace_writeback_queue
Date: Thu, 16 Feb 2012 16:55:17 -0800 [thread overview]
Message-ID: <20120217005511.008575233@linuxfoundation.org> (raw)
In-Reply-To: <20120217005650.GA17119@kroah.com>
3.0-stable review patch. If anyone has any objections, please let me know.
------------------
From: Wu Fengguang <fengguang.wu@intel.com>
commit 977b7e3a52a7421ad33a393a38ece59f3d41c2fa upstream.
When a SD card is hot removed without umount, del_gendisk() will call
bdi_unregister() without destroying/freeing it. This leaves the bdi in
the bdi->dev = NULL, bdi->wb.task = NULL, bdi->bdi_list removed state.
When sync(2) gets the bdi before bdi_unregister() and calls
bdi_queue_work() after the unregister, trace_writeback_queue will be
dereferencing the NULL bdi->dev. Fix it with a simple test for NULL.
LKML-reference: http://lkml.org/lkml/2012/1/18/346
Reported-by: Rabin Vincent <rabin@rab.in>
Tested-by: Namjae Jeon <linkinjeon@gmail.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/trace/events/writeback.h | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
--- a/include/trace/events/writeback.h
+++ b/include/trace/events/writeback.h
@@ -23,7 +23,10 @@ DECLARE_EVENT_CLASS(writeback_work_class
__field(int, for_background)
),
TP_fast_assign(
- strncpy(__entry->name, dev_name(bdi->dev), 32);
+ struct device *dev = bdi->dev;
+ if (!dev)
+ dev = default_backing_dev_info.dev;
+ strncpy(__entry->name, dev_name(dev), 32);
__entry->nr_pages = work->nr_pages;
__entry->sb_dev = work->sb ? work->sb->s_dev : 0;
__entry->sync_mode = work->sync_mode;
next prev parent reply other threads:[~2012-02-17 0:59 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-17 0:56 [00/15] 3.0.22-stable review Greg KH
2012-02-17 0:55 ` [01/15] perf evsel: Fix an issue where perf report fails to show the proper percentage Greg KH
2012-02-17 0:55 ` [02/15] perf tools: Fix perf stack to non executable on x86_64 Greg KH
2012-02-17 0:55 ` [03/15] drm/i915: no lvds quirk for AOpen MP45 Greg KH
2012-02-17 0:55 ` [04/15] hwmon: (f75375s) Fix bit shifting in f75375_write16 Greg KH
2012-02-17 0:55 ` [05/15] lib: proportion: lower PROP_MAX_SHIFT to 32 on 64-bit kernel Greg KH
2012-02-17 0:55 ` [06/15] relay: prevent integer overflow in relay_open() Greg KH
2012-02-17 0:55 ` [07/15] mac80211: timeout a single frame in the rx reorder buffer Greg KH
2012-02-17 0:55 ` Greg KH [this message]
2012-02-17 0:55 ` [09/15] gpio/pca953x: Fix warning of enabled interrupts in handler Greg KH
2012-02-17 0:55 ` [10/15] hwmon: (f75375s) Fix automatic pwm mode setting for F75373 & F75375 Greg KH
2012-02-17 0:55 ` [11/15] crypto: sha512 - Use binary and instead of modulus Greg KH
2012-02-17 0:55 ` [12/15] crypto: sha512 - Avoid stack bloat on i386 Greg KH
2012-02-17 0:55 ` [13/15] ALSA: intel8x0: Fix default inaudible sound on Gateway M520 Greg KH
2012-02-17 0:55 ` [14/15] xen pvhvm: do not remap pirqs onto evtchns if !xen_have_vector_callback Greg KH
2012-02-17 0:55 ` [15/15] slub: fix a possible memleak in __slab_alloc() Greg KH
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