libata: add refcounting to ata_host
After commit 9a6d6a2ddabb ("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: 9a6d6a2ddabb ("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>
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 61b0996..b8b85bf 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -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++) {