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Message-ID: <20170811143649.GA32381@lst.de>
Date: Fri, 11 Aug 2017 16:36:49 +0200
From: Christoph Hellwig <hch@....de>
To: Benjamin Block <bblock@...ux.vnet.ibm.com>
Cc: Christoph Hellwig <hch@....de>,
"James E . J . Bottomley" <jejb@...ux.vnet.ibm.com>,
"Martin K . Petersen" <martin.petersen@...cle.com>,
Jens Axboe <axboe@...nel.dk>, linux-block@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-scsi@...r.kernel.org,
Johannes Thumshirn <jthumshirn@...e.de>,
Steffen Maier <maier@...ux.vnet.ibm.com>,
open-iscsi@...glegroups.com
Subject: Re: [RFC PATCH 1/6] bsg: fix kernel panic resulting from missing
allocation of a reply-buffer
On Fri, Aug 11, 2017 at 03:49:29PM +0200, Benjamin Block wrote:
> On Fri, Aug 11, 2017 at 11:14:15AM +0200, Christoph Hellwig wrote:
> > But patch 1 still creates an additional copy of the sense data for
> > all bsg users.
> >
>
> Huh? What additional copy? There is one reply-buffer and that is copied
> into the user-buffer should it contain valid data. Just like in your
> patch, neither you, nor me touches any of the copy-code. There is also
> no changes to how the driver get their data into that buffer, it will
> still be copied in both cases.
You're right - I misread your patch. But that does make it worse as
this means that with your patch we re-assign the scsi_request.sense
pointer when using bsg. That will lead to crashes if using the bsg
code against e.g. a normal scsi device using bsg when that request
later gets reused for something that is not bsg.
>
> >
> > Can you test the patch below which implements my suggestion? Your
> > other patches should still apply fine on top modulo minor context
> > changes.
>
> Only your patch on top of 4.13-rc4. din_xferp (D) is also empty, which is
> not taken from the sense-buffer.
Can't parse this.
> =============================================================================
> BUG kmalloc-1024 (Not tainted): Invalid object pointer 0x000000004ad9e0f0
> -----------------------------------------------------------------------------
Oops - if we don't allocate the job separately we should not free it either.
Updated patch for that below:
---
>From 4cd32ee48e334b62b55bff0d380833b978454040 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@....de>
Date: Fri, 11 Aug 2017 11:03:29 +0200
Subject: bsg-lib: allocate sense data for each request
Since we split the scsi_request out of the request the driver is supposed
to provide storage for the sense buffer. The bsg-lib code failed to do so,
though and will crash anytime it is used.
This patch moves bsg-lib to allocate and setup the bsg_job ahead of time,
and allocate the sense data, which is used as reply buffer in bsg.
Reported-by: Steffen Maier <maier@...ux.vnet.ibm.com>
Signed-off-by: Benjamin Block <bblock@...ux.vnet.ibm.com>
Fixes: 82ed4db499b8 ("block: split scsi_request out of struct request")
Cc: <stable@...r.kernel.org> #4.11+
---
block/bsg-lib.c | 53 +++++++++++++++++++++++++++----------------------
include/linux/blkdev.h | 1 -
include/linux/bsg-lib.h | 2 ++
3 files changed, 31 insertions(+), 25 deletions(-)
diff --git a/block/bsg-lib.c b/block/bsg-lib.c
index c4513b23f57a..215893dbd038 100644
--- a/block/bsg-lib.c
+++ b/block/bsg-lib.c
@@ -100,7 +100,7 @@ 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);
}
@@ -129,26 +129,9 @@ static int bsg_map_buffer(struct bsg_buffer *buf, struct request *req)
static int bsg_create_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 +170,6 @@ 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))
@@ -207,8 +189,7 @@ 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 +200,29 @@ 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);
+
+ memset(job, 0, sizeof(*job));
+ job->req = req;
+ job->dd_data = job + 1;
+ job->request = job->sreq.cmd;
+ job->request_len = job->sreq.cmd_len;
+ job->reply_len = SCSI_SENSE_BUFFERSIZE;
+ job->reply = job->sreq.sense = kzalloc(job->reply_len, gfp);
+ if (!job->reply)
+ return -ENOMEM;
+ return 0;
+}
+
+static void bsg_exit_rq(struct request_queue *q, struct request *req)
+{
+ struct bsg_job *job = blk_mq_rq_to_pdu(req);
+
+ kfree(job->reply);
+}
+
/**
* bsg_setup_queue - Create and add the bsg hooks so we can receive requests
* @dev: device to attach bsg device to
@@ -235,7 +239,9 @@ 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 +249,6 @@ 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 f45f157b2910..6ae9aa6f93f0 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 <linux/blkdev.h>
+#include <scsi/scsi_request.h>
struct request;
struct device;
@@ -37,6 +38,7 @@ struct bsg_buffer {
};
struct bsg_job {
+ struct scsi_request sreq;
struct device *dev;
struct request *req;
--
2.11.0
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