[PATCH 3.2 178/185] aacraid: prevent invalid pointer dereference

[Ben Hutchings]

3.2.54-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Mahesh Rajashekhara <Mahesh.Rajashekhara@xxxxxxxx>

commit b4789b8e6be3151a955ade74872822f30e8cd914 upstream.

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.

It is 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@xxxxxxxx>
Reported-by: Nico Golde <nico@xxxxxxxxx>
Reported-by: Fabian Yamaguchi <fabs@xxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/scsi/aacraid/commctrl.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/scsi/aacraid/commctrl.c
+++ b/drivers/scsi/aacraid/commctrl.c
@@ -508,7 +508,8 @@ static int aac_send_raw_srb(struct aac_d
 		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;
 	}

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