Re: [PATCH] i40iw: Add missing NULL check for MPA private data

On Tue, Aug 23, 2016 at 12:47:35PM -0400, Doug Ledford wrote:

On 8/22/2016 7:16 PM, Shiraz Saleem wrote:

quoted

Add NULL check for pdata and pdata->addr before the memcpy in
i40iw_form_cm_frame(). This fixes a NULL pointer de-reference
which occurs when the MPA private data pointer is NULL. Also
only copy pdata->size bytes in the memcpy to prevent reading
past the length of the private data buffer provided by upper layer.

Fixes: f27b4746f378 ("i40iw: add connection management code")

Reported-by: Stefan Assmann <redacted>
Signed-off-by: Mustafa Ismail <redacted>
Signed-off-by: Shiraz Saleem <redacted>
---
 drivers/infiniband/hw/i40iw/i40iw_cm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/hw/i40iw/i40iw_cm.c b/drivers/infiniband/hw/i40iw/i40iw_cm.c
index 5026dc7..6434398 100644
--- a/drivers/infiniband/hw/i40iw/i40iw_cm.c
+++ b/drivers/infiniband/hw/i40iw/i40iw_cm.c

@@ -535,8 +535,8 @@ static struct i40iw_puda_buf *i40iw_form_cm_frame(struct i40iw_cm_node *cm_node,
 		buf += hdr_len;
 	}
 
-	if (pd_len)
-		memcpy(buf, pdata->addr, pd_len);
+	if (pdata && pdata->addr)
+		memcpy(buf, pdata->addr, pdata->size);

Is there a guarantee that pdata->size is always less than pd_len?  Do
you need a check here?

pd_len is 'always' greater than or equal to pdata->size. In i40iw_form_cm_frame(), 
pd_len starts out as pdata->size and then may be incremented by 4.

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