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SubjectRe: [PATCH] scsi: csiostor: avoid null pointer dereference on card_fw allocation failure
On Wed, Aug 01, 2018 at 05:17:43PM +0100, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
>
> Currently if card_fw fails to be allocated then a null pointer
> dereference occurs on card_fd when calling csio_hw_prep_fw. Fix this
> by checking for a failed allocation and returning -ENOMEM.
>
> Detected by CoverityScan, CID#1271213 ("Dereference null return value")
>
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
> drivers/scsi/csiostor/csio_hw.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/scsi/csiostor/csio_hw.c b/drivers/scsi/csiostor/csio_hw.c
> index a10cf25ee7f9..aa637e9ea9ba 100644
> --- a/drivers/scsi/csiostor/csio_hw.c
> +++ b/drivers/scsi/csiostor/csio_hw.c
> @@ -2275,8 +2275,8 @@ static int csio_hw_prep_fw(struct csio_hw *hw, struct fw_info *fw_info,
> }
>
> /*
> - * Returns -EINVAL if attempts to flash the firmware failed
> - * else returns 0,
> + * Returns -EINVAL if attempts to flash the firmware failed,
> + * -ENOMEM if allocation failed, else returns 0,
> * if flashing was not attempted because the card had the
> * latest firmware ECANCELED is returned
> */
> @@ -2321,6 +2321,8 @@ csio_hw_flash_fw(struct csio_hw *hw, int *reset)
> * card
> */
> card_fw = kmalloc(sizeof(*card_fw), GFP_KERNEL);
> + if (!card_fw)
> + return -ENOMEM;
>
> /* upgrade FW logic */
> ret = csio_hw_prep_fw(hw, fw_info, fw_data, fw_size, card_fw,

There is a call to release_firmware() after csio_hw_prep_hw()

/* upgrade FW logic */
ret = csio_hw_prep_fw(hw, fw_info, fw_data, fw_size, card_fw,
hw->fw_state, reset);

/* Cleaning up */
if (fw != NULL)
release_firmware(fw);

In case of memory allocation failure csio_hw_flash_fw() will return without
calling release_firmware() with this patch.

Following patch fixes this issue

csio_hw_flash_fw(struct csio_hw *hw, int *reset)
return -EINVAL;
}

+ /* allocate memory to read the header of the firmware on the
+ * card
+ */
+ card_fw = kmalloc(sizeof(*card_fw), GFP_KERNEL);
+ if (!card_fw)
+ return -ENOMEM;
+
if (csio_is_t5(pci_dev->device & CSIO_HW_CHIP_MASK))
fw_bin_file = FW_FNAME_T5;
else
csio_hw_flash_fw(struct csio_hw *hw, int *reset)
fw_size = fw->size;
}

- /* allocate memory to read the header of the firmware on the
- * card
- */
- card_fw = kmalloc(sizeof(*card_fw), GFP_KERNEL);
-
/* upgrade FW logic */
ret = csio_hw_prep_fw(hw, fw_info, fw_data, fw_size, card_fw,
hw->fw_state, reset);

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