Re: [PATCH v2] usb: storage: sddr55: Fix a possible null-pointer dereference in sddr55_transport()

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Sorry, I forgot to send to Oliver, so send it again.

On 2019/7/29 19:49, Jia-Ju Bai wrote:
In sddr55_transport(), there is an if statement on line 836 to check
whether info->lba_to_pba is NULL:
     if (info->lba_to_pba == NULL || ...)

When info->lba_to_pba is NULL, it is used on line 948:
     pba = info->lba_to_pba[lba];

Thus, a possible null-pointer dereference may occur.

To fix this bug, info->lba_to_pba is checked before being used.

This bug is found by a static analysis tool STCheck written by us.

Signed-off-by: Jia-Ju Bai <baijiaju1990@xxxxxxxxx>
---
v2:
* Avoid uninitialized access of pba.
   Thank Oliver for helpful advice.

---
  drivers/usb/storage/sddr55.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/storage/sddr55.c b/drivers/usb/storage/sddr55.c
index b8527c55335b..d23aff16091e 100644
--- a/drivers/usb/storage/sddr55.c
+++ b/drivers/usb/storage/sddr55.c
@@ -945,7 +945,7 @@ static int sddr55_transport(struct scsi_cmnd *srb, struct us_data *us)
  			return USB_STOR_TRANSPORT_FAILED;
  		}
- pba = info->lba_to_pba[lba];
+		pba = info->lba_to_pba ? info->lba_to_pba[lba] : 0;
if (srb->cmnd[0] == WRITE_10) {
  			usb_stor_dbg(us, "WRITE_10: write block %04X (LBA %04X) page %01X pages %d\n",




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