Hello, Andrey.
On Wed, Sep 02, 2015 at 01:08:52PM +0200, Andrey Konovalov wrote:
> While running KASAN on 4.2 with Trinity I got the following report:
>
> ==================================================================
> BUG: KASan: use after free in page_cache_async_readahead+0x2cb/0x3f0
> at addr ffff880034bf6690
> Read of size 8 by task sshd/2571
> =============================================================================
> BUG kmalloc-16 (Tainted: G W ): kasan: bad access detected
> -----------------------------------------------------------------------------
>
> Disabling lock debugging due to kernel taint
> INFO: Allocated in bdi_init+0x168/0x960 age=554826 cpu=0 pid=6
Can you please verify that the following patch fixes the issue?
Thanks.
---
block/blk-core.c | 2 +-
block/blk-sysfs.c | 1 +
include/linux/backing-dev.h | 6 +++++-
mm/backing-dev.c | 12 +++++++++++-
4 files changed, 18 insertions(+), 3 deletions(-)
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -578,7 +578,7 @@ void blk_cleanup_queue(struct request_qu
q->queue_lock = &q->__queue_lock;
spin_unlock_irq(lock);
- bdi_destroy(&q->backing_dev_info);
+ bdi_unregister(&q->backing_dev_info);
/* @q is and will stay empty, shutdown and put */
blk_put_queue(q);
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -502,6 +502,7 @@ static void blk_release_queue(struct kob
struct request_queue *q =
container_of(kobj, struct request_queue, kobj);
+ bdi_exit(&q->backing_dev_info);
blkcg_exit_queue(q);
if (q->elevator) {
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -18,13 +18,17 @@
#include <linux/slab.h>
int __must_check bdi_init(struct backing_dev_info *bdi);
-void bdi_destroy(struct backing_dev_info *bdi);
+void bdi_exit(struct backing_dev_info *bdi);
__printf(3, 4)
int bdi_register(struct backing_dev_info *bdi, struct device *parent,
const char *fmt, ...);
int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
+void bdi_unregister(struct backing_dev_info *bdi);
+
int __must_check bdi_setup_and_register(struct backing_dev_info *, char *);
+void bdi_destroy(struct backing_dev_info *bdi);
+
void wb_start_writeback(struct bdi_writeback *wb, long nr_pages,
bool range_cyclic, enum wb_reason reason);
void wb_start_background_writeback(struct bdi_writeback *wb);
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -823,7 +823,7 @@ static void bdi_remove_from_list(struct
synchronize_rcu_expedited();
}
-void bdi_destroy(struct backing_dev_info *bdi)
+void bdi_unregister(struct backing_dev_info *bdi)
{
/* make sure nobody finds us on the bdi_list anymore */
bdi_remove_from_list(bdi);
@@ -835,9 +835,19 @@ void bdi_destroy(struct backing_dev_info
device_unregister(bdi->dev);
bdi->dev = NULL;
}
+}
+void bdi_exit(struct backing_dev_info *bdi)
+{
+ WARN_ON_ONCE(bdi->dev);
wb_exit(&bdi->wb);
}
+
+void bdi_destroy(struct backing_dev_info *bdi)
+{
+ bdi_unregister(bdi);
+ bdi_exit(bdi);
+}
EXPORT_SYMBOL(bdi_destroy);
/*
--
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