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libata: add refcounting to ata_host 

After commit 9a6d6a2dda ("ata: make ata port as parent device of scsi
host") manual driver unbind/remove causes use-after-free.

Unbind unconditionally invokes devres_release_all() which calls
ata_host_release() and frees ata_host/ata_port memory while it is still
being referenced as a parent of SCSI host. When SCSI host is finally
released scsi_host_dev_release() calls put_device(parent) and accesses
freed ata_port memory.

Add reference counting to make sure that ata_host lives long enough.

Bug report: https://lkml.org/lkml/2017/11/1/945
Fixes: 9a6d6a2dda ("ata: make ata port as parent device of scsi host")
Cc: Tejun Heo <tj@kernel.org>
Cc: Lin Ming <minggr@gmail.com>
Cc: linux-ide@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Taras Kondratiuk <takondra@cisco.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Taras Kondratiuk 2018-03-09 08:34:41 +00:00 committed by Tejun Heo
parent a80ea4cb94
commit 2623c7a5f2
4 changed files with 43 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

44
drivers/ata/libata-core.c
View File

@ -6005,7 +6005,7 @@ struct ata_port *ata_port_alloc(struct ata_host *host)
return ap;
}
static void ata_host_release(struct device *gendev, void *res)
static void ata_devres_release(struct device *gendev, void *res)
{
struct ata_host *host = dev_get_drvdata(gendev);
int i;
@ -6019,13 +6019,36 @@ static void ata_host_release(struct device *gendev, void *res)
if (ap->scsi_host)
scsi_host_put(ap->scsi_host);
}
dev_set_drvdata(gendev, NULL);
ata_host_put(host);
}
static void ata_host_release(struct kref *kref)
{
struct ata_host *host = container_of(kref, struct ata_host, kref);
int i;
for (i = 0; i < host->n_ports; i++) {
struct ata_port *ap = host->ports[i];
kfree(ap->pmp_link);
kfree(ap->slave_link);
kfree(ap);
host->ports[i] = NULL;
}
kfree(host);
}
dev_set_drvdata(gendev, NULL);
void ata_host_get(struct ata_host *host)
{
kref_get(&host->kref);
}
void ata_host_put(struct ata_host *host)
{
kref_put(&host->kref, ata_host_release);
}
/**
@ -6053,26 +6076,31 @@ struct ata_host *ata_host_alloc(struct device *dev, int max_ports)
struct ata_host *host;
size_t sz;
int i;
void *dr;
DPRINTK("ENTER\n");
/* alloc a container for our list of ATA ports (buses) */
sz = sizeof(struct ata_host) + (max_ports + 1) * sizeof(void *);
host = kzalloc(sz, GFP_KERNEL);
if (!host)
return NULL;
if (!devres_open_group(dev, NULL, GFP_KERNEL))
return NULL;
/* alloc a container for our list of ATA ports (buses) */
sz = sizeof(struct ata_host) + (max_ports + 1) * sizeof(void *);
/* alloc a container for our list of ATA ports (buses) */
host = devres_alloc(ata_host_release, sz, GFP_KERNEL);
if (!host)
dr = devres_alloc(ata_devres_release, 0, GFP_KERNEL);
if (!dr)
goto err_out;
devres_add(dev, host);
devres_add(dev, dr);
dev_set_drvdata(dev, host);
spin_lock_init(&host->lock);
mutex_init(&host->eh_mutex);
host->dev = dev;
host->n_ports = max_ports;
kref_init(&host->kref);
/* allocate ports bound to this host */
for (i = 0; i < max_ports; i++) {

4
drivers/ata/libata-transport.c
View File

@ -224,6 +224,8 @@ static DECLARE_TRANSPORT_CLASS(ata_port_class,
static void ata_tport_release(struct device *dev)
{
struct ata_port *ap = tdev_to_port(dev);
ata_host_put(ap->host);
}
/**
@ -284,6 +286,7 @@ int ata_tport_add(struct device *parent,
dev->type = &ata_port_type;
dev->parent = parent;
ata_host_get(ap->host);
dev->release = ata_tport_release;
dev_set_name(dev, "ata%d", ap->print_id);
transport_setup_device(dev);
@ -314,6 +317,7 @@ int ata_tport_add(struct device *parent,
tport_err:
transport_destroy_device(dev);
put_device(dev);
ata_host_put(ap->host);
return error;
}

2
drivers/ata/libata.h
View File

@ -100,6 +100,8 @@ extern int ata_port_probe(struct ata_port *ap);
extern void __ata_port_probe(struct ata_port *ap);
extern unsigned int ata_read_log_page(struct ata_device *dev, u8 log,
u8 page, void *buf, unsigned int sectors);
extern void ata_host_get(struct ata_host *host);
extern void ata_host_put(struct ata_host *host);
#define to_ata_port(d) container_of(d, struct ata_port, tdev)

1
include/linux/libata.h
View File

@ -617,6 +617,7 @@ struct ata_host {
void *private_data;
struct ata_port_operations *ops;
unsigned long flags;
struct kref kref;
struct mutex eh_mutex;
struct task_struct *eh_owner;