In function lpfc_xcvr_data_show, the memory allocation with kmalloc might
fail, thereby making rdp_context a null pointer. In the following context
and functions that use this pointer, there are dereferencing operations,
leading to null pointer dereference.

To fix this issue, a null pointer check should be added. If it is null,
use scnprintf to notify the user and return len.

Fixes: 479b0917e447 ("scsi: lpfc: Create a sysfs entry called lpfc_xcvr_data for transceiver info")
Signed-off-by: Huai-Yuan Liu <qq810974084@gmail.com>
---
V2:
* In patch V2, we have removed the unnecessary 'out of memory' message.
  Thank Bart Van Assche for helpful advice.
V3:
* In patch V3, we return len directly instead of goto out_free_rdp.
  Thanks to Justin Tee for his suuestion.
V4:
* In patch V4, we log something before return len, which would result in a
silent when len is 0.
  Thanks to Justin Tee again for additional explanation.
---
 drivers/scsi/lpfc/lpfc_attr.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/scsi/lpfc/lpfc_attr.c b/drivers/scsi/lpfc/lpfc_attr.c
index a46c73e8d7c4..0a9d6978cb0c 100644
--- a/drivers/scsi/lpfc/lpfc_attr.c
+++ b/drivers/scsi/lpfc/lpfc_attr.c
@@ -1907,6 +1907,11 @@ lpfc_xcvr_data_show(struct device *dev, struct device_attribute *attr,
 
 	/* Get transceiver information */
 	rdp_context = kmalloc(sizeof(*rdp_context), GFP_KERNEL);
+	if (!rdp_context) {
+		len = scnprintf(buf, PAGE_SIZE - len,
+				"SPF info NA: alloc failure\n");
+		return len;
+	}
 
 	rc = lpfc_get_sfp_info_wait(phba, rdp_context);
 	if (rc) {
-- 
2.34.1

On Fri, 21 Jun 2024 16:25:45 +0800, Huai-Yuan Liu wrote:

> In function lpfc_xcvr_data_show, the memory allocation with kmalloc might
> fail, thereby making rdp_context a null pointer. In the following context
> and functions that use this pointer, there are dereferencing operations,
> leading to null pointer dereference.
> 
> To fix this issue, a null pointer check should be added. If it is null,
> use scnprintf to notify the user and return len.
> 
> [...]

Applied to 6.11/scsi-queue, thanks!

[1/1] scsi: lpfc: Fix a possible null pointer dereference
      https://git.kernel.org/mkp/scsi/c/5e0bf3e8aec2

-- 
Martin K. Petersen	Oracle Linux Engineering

Hi Huai-Yuan,

Looks good, thanks.

Reviewed-by: Justin Tee <justin.tee@broadcom.com>

Regards,
Justin