[PATCH 1/1] aacraid: prevent ZERO_SIZE_PTR dereference

[PATCH 1/1] aacraid: prevent ZERO_SIZE_PTR dereference

[Mahesh Rajashekhara]

It appears that driver runs into a problem here if fibsize is too small because we allocate user_srbcmd with fibsize size only but later we access it until user_srbcmd->sg.count to copy it over to srbcmd. Seems to be not correct to test (fibsize < sizeof(*user_srbcmd)) because this structure already includes one sg element and this is not needed for commands without data. So, we would recommend to add the following (instead of test for fibsize == 0).

Signed-off-by: Mahesh Rajashekhara <Mahesh.Rajashekhara@pmcs.com>
---
 drivers/scsi/aacraid/commctrl.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/drivers/scsi/aacraid/commctrl.c b/drivers/scsi/aacraid/commctrl.c
index d85ac1a..fbcd48d 100644
--- a/drivers/scsi/aacraid/commctrl.c
+++ b/drivers/scsi/aacraid/commctrl.c
@@ -511,7 +511,8 @@ static int aac_send_raw_srb(struct aac_dev* dev, void __user * arg)
 		goto cleanup;
 	}
 
-	if (fibsize > (dev->max_fib_size - sizeof(struct aac_fibhdr))) {
+	if ((fibsize < (sizeof(struct user_aac_srb) - sizeof(struct user_sgentry))) ||
+	    (fibsize > (dev->max_fib_size - sizeof(struct aac_fibhdr)))) {
 		rcode = -EINVAL;
 		goto cleanup;
 	}
-- 
1.7.7.3

Re: [PATCH 1/1] aacraid: prevent ZERO_SIZE_PTR dereference

[Dan Carpenter]

On Thu, Oct 31, 2013 at 02:01:02PM +0530, Mahesh Rajashekhara wrote:
> It appears that driver runs into a problem here if fibsize is too small because we allocate user_srbcmd with fibsize size only but later we access it until user_srbcmd->sg.count to copy it over to srbcmd. Seems to be not correct to test (fibsize < sizeof(*user_srbcmd)) because this structure already includes one sg element and this is not needed for commands without data. So, we would recommend to add the following (instead of test for fibsize == 0).
> 

Don't forget the reported by tags.

Reported-by: Nico Golde <nico@ngolde.de>
Reported-by: Fabian Yamaguchi <fabs@goesec.de>

regards,
dan carpenter