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| author | Coly Li <colyli@suse.de> | 2017-10-13 16:35:29 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-11-30 08:39:03 +0000 |
| commit | 770e10817e0980b61fa04f99432b1482242d65b4 (patch) | |
| tree | a770b1f62e9c18b0ce0ef9b6f5b89e61dd81bc54 | |
| parent | a1e25420a47a55784f277363ee0b76b2e2ea981d (diff) | |
| download | linux-stable-770e10817e0980b61fa04f99432b1482242d65b4.tar.gz linux-stable-770e10817e0980b61fa04f99432b1482242d65b4.tar.bz2 linux-stable-770e10817e0980b61fa04f99432b1482242d65b4.zip | |
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>
| -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 ca4abe1ccd8d..3fba31cea66e 100644 --- a/drivers/md/bcache/alloc.c +++ b/drivers/md/bcache/alloc.c @@ -404,7 +404,8 @@ 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); |