From: Liang Chen Date: Fri, 13 Oct 2017 23:35:40 +0000 (-0700) Subject: bcache: safeguard a dangerous addressing in closure_queue X-Git-Tag: v5.15~10032^2~121 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=6446c684f9418d0175c9c3e5134e7744fe79181a;p=platform%2Fkernel%2Flinux-starfive.git bcache: safeguard a dangerous addressing in closure_queue The use of the union reduces the size of closure struct by taking advantage of the current size of its members. The offset of func in work_struct equals the size of the first three members, so that work.work_func will just reference the forth member - fn. This is smart but dangerous. It can be broken if work_struct or the other structs get changed, and can be a bit difficult to debug. Signed-off-by: Liang Chen Reviewed-by: Michael Lyle Signed-off-by: Jens Axboe --- diff --git a/drivers/md/bcache/closure.h b/drivers/md/bcache/closure.h index 295b7e4..00fb314 100644 --- a/drivers/md/bcache/closure.h +++ b/drivers/md/bcache/closure.h @@ -251,6 +251,12 @@ static inline void set_closure_fn(struct closure *cl, closure_fn *fn, static inline void closure_queue(struct closure *cl) { struct workqueue_struct *wq = cl->wq; + /** + * Changes made to closure, work_struct, or a couple of other structs + * may cause work.func not pointing to the right location. + */ + BUILD_BUG_ON(offsetof(struct closure, fn) + != offsetof(struct work_struct, func)); if (wq) { INIT_WORK(&cl->work, cl->work.func); BUG_ON(!queue_work(wq, &cl->work));