Re: [patch 1/2] staging: dgnc: some off by one bugs

[Dan Carpenter]

On Thu, Mar 12, 2015 at 08:07:39PM +0300, Dan Carpenter wrote:
> "dgnc_NumBoards" is the number of filled out elements in the
> dgnc_Board[] array.  "->nasync" and "->maxports" are the value.

I meant "the *same* value".  I'll resend.

regards,
dan carpenter

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[patch 1/2] staging: dgnc: some off by one bugs

[Dan Carpenter]

"dgnc_NumBoards" is the number of filled out elements in the
dgnc_Board[] array.  "->nasync" and "->maxports" are the value.  They
are the number of channels in the ->channels[] array so these tests
should be ">=" instead of ">" so we avoid reading past the end of the
arrays.

I cleaned up the conditions in dgnc_mgmt_ioctl() a bit.  There was a
work around for the off by one bug in the case where there were no
boards which is no longer needed.  "channel" is unsigned so it can't be
negative.

Signed-off-by: Dan Carpenter 

diff --git a/drivers/staging/dgnc/dgnc_cls.c b/drivers/staging/dgnc/dgnc_cls.c
index bedc522..0d8f154 100644
--- a/drivers/staging/dgnc/dgnc_cls.c
+++ b/drivers/staging/dgnc/dgnc_cls.c
@@ -406,7 +406,7 @@ static inline void cls_parse_isr(struct dgnc_board *brd, 
uint port)
 * verified in the interrupt routine.
 */
 
-   if (port > brd->nasync)
+   if (port >= brd->nasync)
return;
 
ch = brd->channels[port];
diff --git a/drivers/staging/dgnc/dgnc_mgmt.c b/drivers/staging/dgnc/dgnc_mgmt.c
index 5544a8e..01b290e 100644
--- a/drivers/staging/dgnc/dgnc_mgmt.c
+++ b/drivers/staging/dgnc/dgnc_mgmt.c
@@ -196,11 +196,11 @@ long dgnc_mgmt_ioctl(struct file *file, unsigned int cmd, 
unsigned long arg)
channel = ni.channel;
 
/* Verify boundaries on board */
-   if ((board > dgnc_NumBoards) || (dgnc_NumBoards == 0))
+   if (board >= dgnc_NumBoards)
return -ENODEV;
 
/* Verify boundaries on channel */
-   if ((channel < 0) || (channel > dgnc_Board[board]->nasync))
+   if (channel >= dgnc_Board[board]->nasync)
return -ENODEV;
 
ch = dgnc_Board[board]->channels[channel];
diff --git a/drivers/staging/dgnc/dgnc_neo.c b/drivers/staging/dgnc/dgnc_neo.c
index 1268aa9..921e463 100644
--- a/drivers/staging/dgnc/dgnc_neo.c
+++ b/drivers/staging/dgnc/dgnc_neo.c
@@ -407,7 +407,7 @@ static inline void neo_parse_isr(struct dgnc_board *brd, 
uint port)
if (!brd || brd->magic != DGNC_BOARD_MAGIC)
return;
 
-   if (port > brd->maxports)
+   if (port >= brd->maxports)
return;
 
ch = brd->channels[port];
@@ -537,7 +537,7 @@ static inline void neo_parse_lsr(struct dgnc_board *brd, 
uint port)
if (!brd || brd->magic != DGNC_BOARD_MAGIC)
return;
 
-   if (port > brd->maxports)
+   if (port >= brd->maxports)
return;
 
ch = brd->channels[port];
@@ -1019,7 +1019,7 @@ static irqreturn_t neo_intr(int irq, void *voidbrd)
 */
 
/* Verify the port is in range. */
-   if (port > brd->nasync)
+   if (port >= brd->nasync)
continue;
 
ch = brd->channels[port];
diff --git a/drivers/staging/dgnc/dgnc_tty.c b/drivers/staging/dgnc/dgnc_tty.c
index 8179342..4507d4a 100644
--- a/drivers/staging/dgnc/dgnc_tty.c
+++ b/drivers/staging/dgnc/dgnc_tty.c
@@ -1060,7 +1060,7 @@ static int dgnc_tty_open(struct tty_struct *tty, struct 
file *file)
spin_lock_irqsave(&brd->bd_lock, flags);
 
/* If opened device is greater than our number of ports, bail. */
-   if (PORT_NUM(minor) > brd->nasync) {
+   if (PORT_NUM(minor) >= brd->nasync) {
spin_unlock_irqrestore(&brd->bd_lock, flags);
return -ENXIO;
}
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