Re: [External] : [PATCH v2] scsi: scsi_transport_sas: fix error handling in sas_phy_add()

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On 07/11/2022 11:54, Yang Yingliang wrote:
If transport_add_device() fails in sas_phy_add(), but it's not handled,

The wording is hard to understand here. Omit "but" and it's becomes a bit more readable...

it will lead kernel crash because of trying to delete not added device
in transport_remove_device() called from sas_remove_host().

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000108
CPU: 61 PID: 42829 Comm: rmmod Kdump: loaded Tainted: G        W          6.1.0-rc1+ #173
pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : device_del+0x54/0x3d0
lr : device_del+0x37c/0x3d0
Call trace:
  device_del+0x54/0x3d0
  attribute_container_class_device_del+0x28/0x38
  transport_remove_classdev+0x6c/0x80
  attribute_container_device_trigger+0x108/0x110
  transport_remove_device+0x28/0x38
  sas_phy_delete+0x30/0x60 [scsi_transport_sas]
  do_sas_phy_delete+0x6c/0x80 [scsi_transport_sas]
  device_for_each_child+0x68/0xb0
  sas_remove_children+0x40/0x50 [scsi_transport_sas]
  sas_remove_host+0x20/0x38 [scsi_transport_sas]
  hisi_sas_remove+0x40/0x68 [hisi_sas_main]
  hisi_sas_v2_remove+0x20/0x30 [hisi_sas_v2_hw]
  platform_remove+0x2c/0x60

Fix this by checking and handling return value of transport_add_device()
in sas_phy_add().

Fixes: c7ebbbce366c ("[SCSI] SAS transport class")
Suggested-by: John Garry <john.g.garry@xxxxxxxxxx>
Signed-off-by: Yang Yingliang <yangyingliang@xxxxxxxxxx>

Apart from comment about commit message:
Reviewed-by: John Garry <john.g.garry@xxxxxxxxxx>

---
v1 -> v2:
   Update title and refactor the error handling suggested by John.
---
  drivers/scsi/scsi_transport_sas.c | 13 +++++++++----
  1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/scsi_transport_sas.c b/drivers/scsi/scsi_transport_sas.c
index 2f88c61216ee..74b99f2b0b74 100644
--- a/drivers/scsi/scsi_transport_sas.c
+++ b/drivers/scsi/scsi_transport_sas.c
@@ -722,12 +722,17 @@ int sas_phy_add(struct sas_phy *phy)
  	int error;
error = device_add(&phy->dev);
-	if (!error) {
-		transport_add_device(&phy->dev);
-		transport_configure_device(&phy->dev);
+	if (error)
+		return error;
+
+	error = transport_add_device(&phy->dev);
+	if (error) {
+		device_del(&phy->dev);
+		return error;
  	}
+	transport_configure_device(&phy->dev);
- return error;
+	return 0;
  }
  EXPORT_SYMBOL(sas_phy_add);




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