From 76d697d10769048e5721510100bf3a9413a56385 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Tue, 20 Jan 2015 11:00:56 +0800 Subject: [PATCH] blk-mq: fix hctx/ctx kobject use-after-free The kobject memory shouldn't have been freed before the kobject is released because driver core can access it freely before its release. This patch frees hctx in its release callback. For ctx, they share one single per-cpu variable which is associated with the request queue, so free ctx in q->mq_kobj's release handler. Signed-off-by: Sasha Levin (fix ctx kobjects) Signed-off-by: Ming Lei Signed-off-by: Jens Axboe --- block/blk-mq-sysfs.c | 25 +++++++++++++++++++++++-- block/blk-mq.c | 6 +----- 2 files changed, 24 insertions(+), 7 deletions(-) diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c index 1630a20d5dcf..6774a0e69867 100644 --- a/block/blk-mq-sysfs.c +++ b/block/blk-mq-sysfs.c @@ -15,6 +15,26 @@ static void blk_mq_sysfs_release(struct kobject *kobj) { + struct request_queue *q; + + q = container_of(kobj, struct request_queue, mq_kobj); + free_percpu(q->queue_ctx); +} + +static void blk_mq_ctx_release(struct kobject *kobj) +{ + struct blk_mq_ctx *ctx; + + ctx = container_of(kobj, struct blk_mq_ctx, kobj); + kobject_put(&ctx->queue->mq_kobj); +} + +static void blk_mq_hctx_release(struct kobject *kobj) +{ + struct blk_mq_hw_ctx *hctx; + + hctx = container_of(kobj, struct blk_mq_hw_ctx, kobj); + kfree(hctx); } struct blk_mq_ctx_sysfs_entry { @@ -318,13 +338,13 @@ static struct kobj_type blk_mq_ktype = { static struct kobj_type blk_mq_ctx_ktype = { .sysfs_ops = &blk_mq_sysfs_ops, .default_attrs = default_ctx_attrs, - .release = blk_mq_sysfs_release, + .release = blk_mq_ctx_release, }; static struct kobj_type blk_mq_hw_ktype = { .sysfs_ops = &blk_mq_hw_sysfs_ops, .default_attrs = default_hw_ctx_attrs, - .release = blk_mq_sysfs_release, + .release = blk_mq_hctx_release, }; static void blk_mq_unregister_hctx(struct blk_mq_hw_ctx *hctx) @@ -355,6 +375,7 @@ static int blk_mq_register_hctx(struct blk_mq_hw_ctx *hctx) return ret; hctx_for_each_ctx(hctx, ctx, i) { + kobject_get(&q->mq_kobj); ret = kobject_add(&ctx->kobj, &hctx->kobj, "cpu%u", ctx->cpu); if (ret) break; diff --git a/block/blk-mq.c b/block/blk-mq.c index 2f95747c287e..9ee3b87c4498 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1641,10 +1641,8 @@ static void blk_mq_free_hw_queues(struct request_queue *q, struct blk_mq_hw_ctx *hctx; unsigned int i; - queue_for_each_hw_ctx(q, hctx, i) { + queue_for_each_hw_ctx(q, hctx, i) free_cpumask_var(hctx->cpumask); - kfree(hctx); - } } static int blk_mq_init_hctx(struct request_queue *q, @@ -2002,11 +2000,9 @@ void blk_mq_free_queue(struct request_queue *q) percpu_ref_exit(&q->mq_usage_counter); - free_percpu(q->queue_ctx); kfree(q->queue_hw_ctx); kfree(q->mq_map); - q->queue_ctx = NULL; q->queue_hw_ctx = NULL; q->mq_map = NULL; -- 2.30.2