From 50b4d485528d1dbe0bd249f2073140e3444f4a7b Mon Sep 17 00:00:00 2001 From: Benjamin Block Date: Thu, 24 Aug 2017 01:57:56 +0200 Subject: [PATCH] bsg-lib: fix kernel panic resulting from missing allocation of reply-buffer Since we split the scsi_request out of struct request bsg fails to provide a reply-buffer for the drivers. This was done via the pointer for sense-data, that is not preallocated anymore. Failing to allocate/assign it results in illegal dereferences because LLDs use this pointer unquestioned. An example panic on s390x, using the zFCP driver, looks like this (I had debugging on, otherwise NULL-pointer dereferences wouldn't even panic on s390x): Unable to handle kernel pointer dereference in virtual kernel address space Failing address: 6b6b6b6b6b6b6000 TEID: 6b6b6b6b6b6b6403 Fault in home space mode while using kernel ASCE. AS:0000000001590007 R3:0000000000000024 Oops: 0038 ilc:2 [#1] PREEMPT SMP DEBUG_PAGEALLOC Modules linked in: CPU: 2 PID: 0 Comm: swapper/2 Not tainted 4.12.0-bsg-regression+ #3 Hardware name: IBM 2964 N96 702 (z/VM 6.4.0) task: 0000000065cb0100 task.stack: 0000000065cb4000 Krnl PSW : 0704e00180000000 000003ff801e4156 (zfcp_fc_ct_els_job_handler+0x16/0x58 [zfcp]) R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:2 PM:0 RI:0 EA:3 Krnl GPRS: 0000000000000001 000000005fa9d0d0 000000005fa9d078 0000000000e16866 000003ff00000290 6b6b6b6b6b6b6b6b 0000000059f78f00 000000000000000f 00000000593a0958 00000000593a0958 0000000060d88800 000000005ddd4c38 0000000058b50100 07000000659cba08 000003ff801e8556 00000000659cb9a8 Krnl Code: 000003ff801e4146: e31020500004 lg %r1,80(%r2) 000003ff801e414c: 58402040 l %r4,64(%r2) #000003ff801e4150: e35020200004 lg %r5,32(%r2) >000003ff801e4156: 50405004 st %r4,4(%r5) 000003ff801e415a: e54c50080000 mvhi 8(%r5),0 000003ff801e4160: e33010280012 lt %r3,40(%r1) 000003ff801e4166: a718fffb lhi %r1,-5 000003ff801e416a: 1803 lr %r0,%r3 Call Trace: ([<000003ff801e8556>] zfcp_fsf_req_complete+0x726/0x768 [zfcp]) [<000003ff801ea82a>] zfcp_fsf_reqid_check+0x102/0x180 [zfcp] [<000003ff801eb980>] zfcp_qdio_int_resp+0x230/0x278 [zfcp] [<00000000009b91b6>] qdio_kick_handler+0x2ae/0x2c8 [<00000000009b9e3e>] __tiqdio_inbound_processing+0x406/0xc10 [<00000000001684c2>] tasklet_action+0x15a/0x1d8 [<0000000000bd28ec>] __do_softirq+0x3ec/0x848 [<00000000001675a4>] irq_exit+0x74/0xf8 [<000000000010dd6a>] do_IRQ+0xba/0xf0 [<0000000000bd19e8>] io_int_handler+0x104/0x2d4 [<00000000001033b6>] enabled_wait+0xb6/0x188 ([<000000000010339e>] enabled_wait+0x9e/0x188) [<000000000010396a>] arch_cpu_idle+0x32/0x50 [<0000000000bd0112>] default_idle_call+0x52/0x68 [<00000000001cd0fa>] do_idle+0x102/0x188 [<00000000001cd41e>] cpu_startup_entry+0x3e/0x48 [<0000000000118c64>] smp_start_secondary+0x11c/0x130 [<0000000000bd2016>] restart_int_handler+0x62/0x78 [<0000000000000000>] (null) INFO: lockdep is turned off. Last Breaking-Event-Address: [<000003ff801e41d6>] zfcp_fc_ct_job_handler+0x3e/0x48 [zfcp] Kernel panic - not syncing: Fatal exception in interrupt This patch moves bsg-lib to allocate and setup struct bsg_job ahead of time, including the allocation of a buffer for the reply-data. This means, struct bsg_job is not allocated separately anymore, but as part of struct request allocation - similar to struct scsi_cmd. Reflect this in the function names that used to handle creation/destruction of struct bsg_job. Reported-by: Steffen Maier Suggested-by: Christoph Hellwig Reviewed-by: Christoph Hellwig Signed-off-by: Benjamin Block Fixes: 82ed4db499b8 ("block: split scsi_request out of struct request") Cc: #4.11+ Signed-off-by: Jens Axboe --- block/bsg-lib.c | 74 ++++++++++++++++++++++++----------------- include/linux/blkdev.h | 1 - include/linux/bsg-lib.h | 2 ++ 3 files changed, 46 insertions(+), 31 deletions(-) diff --git a/block/bsg-lib.c b/block/bsg-lib.c index c4513b23f57a..dd56d7460cb9 100644 --- a/block/bsg-lib.c +++ b/block/bsg-lib.c @@ -29,26 +29,25 @@ #include /** - * bsg_destroy_job - routine to teardown/delete a bsg job + * bsg_teardown_job - routine to teardown a bsg job * @job: bsg_job that is to be torn down */ -static void bsg_destroy_job(struct kref *kref) +static void bsg_teardown_job(struct kref *kref) { struct bsg_job *job = container_of(kref, struct bsg_job, kref); struct request *rq = job->req; - blk_end_request_all(rq, BLK_STS_OK); - put_device(job->dev); /* release reference for the request */ kfree(job->request_payload.sg_list); kfree(job->reply_payload.sg_list); - kfree(job); + + blk_end_request_all(rq, BLK_STS_OK); } void bsg_job_put(struct bsg_job *job) { - kref_put(&job->kref, bsg_destroy_job); + kref_put(&job->kref, bsg_teardown_job); } EXPORT_SYMBOL_GPL(bsg_job_put); @@ -100,7 +99,7 @@ EXPORT_SYMBOL_GPL(bsg_job_done); */ static void bsg_softirq_done(struct request *rq) { - struct bsg_job *job = rq->special; + struct bsg_job *job = blk_mq_rq_to_pdu(rq); bsg_job_put(job); } @@ -122,33 +121,20 @@ static int bsg_map_buffer(struct bsg_buffer *buf, struct request *req) } /** - * bsg_create_job - create the bsg_job structure for the bsg request + * bsg_prepare_job - create the bsg_job structure for the bsg request * @dev: device that is being sent the bsg request * @req: BSG request that needs a job structure */ -static int bsg_create_job(struct device *dev, struct request *req) +static int bsg_prepare_job(struct device *dev, struct request *req) { struct request *rsp = req->next_rq; - struct request_queue *q = req->q; struct scsi_request *rq = scsi_req(req); - struct bsg_job *job; + struct bsg_job *job = blk_mq_rq_to_pdu(req); int ret; - BUG_ON(req->special); - - job = kzalloc(sizeof(struct bsg_job) + q->bsg_job_size, GFP_KERNEL); - if (!job) - return -ENOMEM; - - req->special = job; - job->req = req; - if (q->bsg_job_size) - job->dd_data = (void *)&job[1]; job->request = rq->cmd; job->request_len = rq->cmd_len; - job->reply = rq->sense; - job->reply_len = SCSI_SENSE_BUFFERSIZE; /* Size of sense buffer - * allocated */ + if (req->bio) { ret = bsg_map_buffer(&job->request_payload, req); if (ret) @@ -187,7 +173,6 @@ static void bsg_request_fn(struct request_queue *q) { struct device *dev = q->queuedata; struct request *req; - struct bsg_job *job; int ret; if (!get_device(dev)) @@ -199,7 +184,7 @@ static void bsg_request_fn(struct request_queue *q) break; spin_unlock_irq(q->queue_lock); - ret = bsg_create_job(dev, req); + ret = bsg_prepare_job(dev, req); if (ret) { scsi_req(req)->result = ret; blk_end_request_all(req, BLK_STS_OK); @@ -207,8 +192,7 @@ static void bsg_request_fn(struct request_queue *q) continue; } - job = req->special; - ret = q->bsg_job_fn(job); + ret = q->bsg_job_fn(blk_mq_rq_to_pdu(req)); spin_lock_irq(q->queue_lock); if (ret) break; @@ -219,6 +203,35 @@ static void bsg_request_fn(struct request_queue *q) spin_lock_irq(q->queue_lock); } +static int bsg_init_rq(struct request_queue *q, struct request *req, gfp_t gfp) +{ + struct bsg_job *job = blk_mq_rq_to_pdu(req); + struct scsi_request *sreq = &job->sreq; + + memset(job, 0, sizeof(*job)); + + scsi_req_init(sreq); + sreq->sense_len = SCSI_SENSE_BUFFERSIZE; + sreq->sense = kzalloc(sreq->sense_len, gfp); + if (!sreq->sense) + return -ENOMEM; + + job->req = req; + job->reply = sreq->sense; + job->reply_len = sreq->sense_len; + job->dd_data = job + 1; + + return 0; +} + +static void bsg_exit_rq(struct request_queue *q, struct request *req) +{ + struct bsg_job *job = blk_mq_rq_to_pdu(req); + struct scsi_request *sreq = &job->sreq; + + kfree(sreq->sense); +} + /** * bsg_setup_queue - Create and add the bsg hooks so we can receive requests * @dev: device to attach bsg device to @@ -235,7 +248,9 @@ struct request_queue *bsg_setup_queue(struct device *dev, char *name, q = blk_alloc_queue(GFP_KERNEL); if (!q) return ERR_PTR(-ENOMEM); - q->cmd_size = sizeof(struct scsi_request); + q->cmd_size = sizeof(struct bsg_job) + dd_job_size; + q->init_rq_fn = bsg_init_rq; + q->exit_rq_fn = bsg_exit_rq; q->request_fn = bsg_request_fn; ret = blk_init_allocated_queue(q); @@ -243,7 +258,6 @@ struct request_queue *bsg_setup_queue(struct device *dev, char *name, goto out_cleanup_queue; q->queuedata = dev; - q->bsg_job_size = dd_job_size; q->bsg_job_fn = job_fn; queue_flag_set_unlocked(QUEUE_FLAG_BIDI, q); queue_flag_set_unlocked(QUEUE_FLAG_SCSI_PASSTHROUGH, q); diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 25f6a0cb27d3..2a5d52fa90f5 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -568,7 +568,6 @@ struct request_queue { #if defined(CONFIG_BLK_DEV_BSG) bsg_job_fn *bsg_job_fn; - int bsg_job_size; struct bsg_class_device bsg_dev; #endif diff --git a/include/linux/bsg-lib.h b/include/linux/bsg-lib.h index e34dde2da0ef..637a20cfb237 100644 --- a/include/linux/bsg-lib.h +++ b/include/linux/bsg-lib.h @@ -24,6 +24,7 @@ #define _BLK_BSG_ #include +#include struct request; struct device; @@ -37,6 +38,7 @@ struct bsg_buffer { }; struct bsg_job { + struct scsi_request sreq; struct device *dev; struct request *req;