diff options
| author | Coly Li <colyli@suse.de> | 2017-10-13 16:35:29 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-11-30 08:37:20 +0000 |
| commit | 85c79043808d400ace74c99526fb9f4f67253102 (patch) | |
| tree | ce6aeef135ca5621662195b1b678cc6474aa6c2b /drivers/md | |
| parent | 9c093a258350e86f781f23fbbef4e3d761c6b1e3 (diff) | |
bcache: check ca->alloc_thread initialized before wake up it
commit 91af8300d9c1d7c6b6a2fd754109e08d4798b8d8 upstream.
In bcache code, sysfs entries are created before all resources get
allocated, e.g. allocation thread of a cache set.
There is posibility for NULL pointer deference if a resource is accessed
but which is not initialized yet. Indeed Jorg Bornschein catches one on
cache set allocation thread and gets a kernel oops.
The reason for this bug is, when bch_bucket_alloc() is called during
cache set registration and attaching, ca->alloc_thread is not properly
allocated and initialized yet, call wake_up_process() on ca->alloc_thread
triggers NULL pointer deference failure. A simple and fast fix is, before
waking up ca->alloc_thread, checking whether it is allocated, and only
wake up ca->alloc_thread when it is not NULL.
Signed-off-by: Coly Li <colyli@suse.de>
Reported-by: Jorg Bornschein <jb@capsec.org>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Reviewed-by: Michael Lyle <mlyle@lyle.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/bcache/alloc.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/md/bcache/alloc.c b/drivers/md/bcache/alloc.c index 8eeab72b93e2..ea47980949ef 100644 --- a/drivers/md/bcache/alloc.c +++ b/drivers/md/bcache/alloc.c @@ -406,7 +406,8 @@ long bch_bucket_alloc(struct cache *ca, unsigned reserve, bool wait) finish_wait(&ca->set->bucket_wait, &w); out: - wake_up_process(ca->alloc_thread); + if (ca->alloc_thread) + wake_up_process(ca->alloc_thread); trace_bcache_alloc(ca, reserve); |