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authorBart Van Assche <bart.vanassche@sandisk.com>2017-06-02 14:21:52 -0700
committerMartin K. Petersen <martin.petersen@oracle.com>2017-06-12 20:55:58 -0400
commit8e6882545d8c06f99e9e117741cc87f3338b0bef (patch)
tree12a6bb40ee60e460788b3b45cddce7326dba6a4f /drivers/scsi/scsi_lib.c
parent896f6966fc815abe71f85fb26f0193875df8a035 (diff)
scsi: Avoid that scsi_exit_rq() triggers a use-after-free
Dereferencing shost from scsi_exit_rq() is not safe because the SCSI host may already have been freed when scsi_exit_rq() is called. Increasing the shost reference count in scsi_init_rq() and dropping that reference in scsi_exit_rq() is nontrivial since scsi_host_dev_release() may sleep and since scsi_exit_rq() may be called from interrupt context. Since scsi_exit_rq() only needs a single bit from shost, copy that bit into struct scsi_cmnd. Reported-by: Scott Bauer <scott.bauer@intel.com> Fixes: e9c787e65c0c ("scsi: allocate scsi_cmnd structures as part of struct request") Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Cc: Hannes Reinecke <hare@suse.com> Cc: Scott Bauer <scott.bauer@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: <stable@vger.kernel.org> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/scsi/scsi_lib.c')
-rw-r--r--drivers/scsi/scsi_lib.c47
1 files changed, 29 insertions, 18 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 99e16ac479e3..a95eb022fb89 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -45,23 +45,23 @@ static struct kmem_cache *scsi_sense_isadma_cache;
static DEFINE_MUTEX(scsi_sense_cache_mutex);
static inline struct kmem_cache *
-scsi_select_sense_cache(struct Scsi_Host *shost)
+scsi_select_sense_cache(bool unchecked_isa_dma)
{
- return shost->unchecked_isa_dma ?
- scsi_sense_isadma_cache : scsi_sense_cache;
+ return unchecked_isa_dma ? scsi_sense_isadma_cache : scsi_sense_cache;
}
-static void scsi_free_sense_buffer(struct Scsi_Host *shost,
- unsigned char *sense_buffer)
+static void scsi_free_sense_buffer(bool unchecked_isa_dma,
+ unsigned char *sense_buffer)
{
- kmem_cache_free(scsi_select_sense_cache(shost), sense_buffer);
+ kmem_cache_free(scsi_select_sense_cache(unchecked_isa_dma),
+ sense_buffer);
}
-static unsigned char *scsi_alloc_sense_buffer(struct Scsi_Host *shost,
+static unsigned char *scsi_alloc_sense_buffer(bool unchecked_isa_dma,
gfp_t gfp_mask, int numa_node)
{
- return kmem_cache_alloc_node(scsi_select_sense_cache(shost), gfp_mask,
- numa_node);
+ return kmem_cache_alloc_node(scsi_select_sense_cache(unchecked_isa_dma),
+ gfp_mask, numa_node);
}
int scsi_init_sense_cache(struct Scsi_Host *shost)
@@ -69,7 +69,7 @@ int scsi_init_sense_cache(struct Scsi_Host *shost)
struct kmem_cache *cache;
int ret = 0;
- cache = scsi_select_sense_cache(shost);
+ cache = scsi_select_sense_cache(shost->unchecked_isa_dma);
if (cache)
return 0;
@@ -1138,6 +1138,7 @@ void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd)
{
void *buf = cmd->sense_buffer;
void *prot = cmd->prot_sdb;
+ unsigned int unchecked_isa_dma = cmd->flags & SCMD_UNCHECKED_ISA_DMA;
unsigned long flags;
/* zero out the cmd, except for the embedded scsi_request */
@@ -1147,6 +1148,7 @@ void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd)
cmd->device = dev;
cmd->sense_buffer = buf;
cmd->prot_sdb = prot;
+ cmd->flags = unchecked_isa_dma;
INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler);
cmd->jiffies_at_alloc = jiffies;
@@ -1847,6 +1849,7 @@ static int scsi_mq_prep_fn(struct request *req)
struct scsi_device *sdev = req->q->queuedata;
struct Scsi_Host *shost = sdev->host;
unsigned char *sense_buf = cmd->sense_buffer;
+ unsigned int unchecked_isa_dma = cmd->flags & SCMD_UNCHECKED_ISA_DMA;
struct scatterlist *sg;
/* zero out the cmd, except for the embedded scsi_request */
@@ -1858,6 +1861,7 @@ static int scsi_mq_prep_fn(struct request *req)
cmd->request = req;
cmd->device = sdev;
cmd->sense_buffer = sense_buf;
+ cmd->flags = unchecked_isa_dma;
cmd->tag = req->tag;
@@ -2004,10 +2008,13 @@ static int scsi_init_request(struct blk_mq_tag_set *set, struct request *rq,
unsigned int hctx_idx, unsigned int numa_node)
{
struct Scsi_Host *shost = set->driver_data;
+ const bool unchecked_isa_dma = shost->unchecked_isa_dma;
struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
- cmd->sense_buffer =
- scsi_alloc_sense_buffer(shost, GFP_KERNEL, numa_node);
+ if (unchecked_isa_dma)
+ cmd->flags |= SCMD_UNCHECKED_ISA_DMA;
+ cmd->sense_buffer = scsi_alloc_sense_buffer(unchecked_isa_dma,
+ GFP_KERNEL, numa_node);
if (!cmd->sense_buffer)
return -ENOMEM;
cmd->req.sense = cmd->sense_buffer;
@@ -2017,10 +2024,10 @@ static int scsi_init_request(struct blk_mq_tag_set *set, struct request *rq,
static void scsi_exit_request(struct blk_mq_tag_set *set, struct request *rq,
unsigned int hctx_idx)
{
- struct Scsi_Host *shost = set->driver_data;
struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
- scsi_free_sense_buffer(shost, cmd->sense_buffer);
+ scsi_free_sense_buffer(cmd->flags & SCMD_UNCHECKED_ISA_DMA,
+ cmd->sense_buffer);
}
static int scsi_map_queues(struct blk_mq_tag_set *set)
@@ -2093,11 +2100,15 @@ EXPORT_SYMBOL_GPL(__scsi_init_queue);
static int scsi_init_rq(struct request_queue *q, struct request *rq, gfp_t gfp)
{
struct Scsi_Host *shost = q->rq_alloc_data;
+ const bool unchecked_isa_dma = shost->unchecked_isa_dma;
struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
memset(cmd, 0, sizeof(*cmd));
- cmd->sense_buffer = scsi_alloc_sense_buffer(shost, gfp, NUMA_NO_NODE);
+ if (unchecked_isa_dma)
+ cmd->flags |= SCMD_UNCHECKED_ISA_DMA;
+ cmd->sense_buffer = scsi_alloc_sense_buffer(unchecked_isa_dma, gfp,
+ NUMA_NO_NODE);
if (!cmd->sense_buffer)
goto fail;
cmd->req.sense = cmd->sense_buffer;
@@ -2111,19 +2122,19 @@ static int scsi_init_rq(struct request_queue *q, struct request *rq, gfp_t gfp)
return 0;
fail_free_sense:
- scsi_free_sense_buffer(shost, cmd->sense_buffer);
+ scsi_free_sense_buffer(unchecked_isa_dma, cmd->sense_buffer);
fail:
return -ENOMEM;
}
static void scsi_exit_rq(struct request_queue *q, struct request *rq)
{
- struct Scsi_Host *shost = q->rq_alloc_data;
struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
if (cmd->prot_sdb)
kmem_cache_free(scsi_sdb_cache, cmd->prot_sdb);
- scsi_free_sense_buffer(shost, cmd->sense_buffer);
+ scsi_free_sense_buffer(cmd->flags & SCMD_UNCHECKED_ISA_DMA,
+ cmd->sense_buffer);
}
struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)

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