Re: [wireless-next:master 207/237] drivers/net/wireless/brcm80211/brcmsmac/dma.c:352:20-24: ERROR: di is NULL but dereferenced.

Seth Forshee
2012-11-29T13:51:37Z

On Thu, Nov 29, 2012 at 09:13:37AM +0800, Fengguang Wu wrote:
> Hi Seth,
>
> FYI, there are coccinelle warnings in
>
> tree: git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-next.git master
> head: 0751f8654602e4255f0b9c17784d8100d5896010
> commit: 90123e045cac4ce8ec13e266f030c618fa674554 [207/237] brcmsmac: Add brcms_dbg_dma() debug macro
>
> + drivers/net/wireless/brcm80211/brcmsmac/dma.c:352:20-24: ERROR: di is NULL but dereferenced.
>
> vim +352 drivers/net/wireless/brcm80211/brcmsmac/dma.c
>
> 5b435de0 Arend van Spriel 2011-10-05 336
> 5b435de0 Arend van Spriel 2011-10-05 337 static uint ntxdactive(struct dma_info *di, uint h, uint t)
> 5b435de0 Arend van Spriel 2011-10-05 338 {
> 5b435de0 Arend van Spriel 2011-10-05 339 return txd(di, t-h);
> 5b435de0 Arend van Spriel 2011-10-05 340 }
> 5b435de0 Arend van Spriel 2011-10-05 341
> 5b435de0 Arend van Spriel 2011-10-05 342 static uint nrxdactive(struct dma_info *di, uint h, uint t)
> 5b435de0 Arend van Spriel 2011-10-05 343 {
> 5b435de0 Arend van Spriel 2011-10-05 344 return rxd(di, t-h);
> 5b435de0 Arend van Spriel 2011-10-05 345 }
> 5b435de0 Arend van Spriel 2011-10-05 346
> 5b435de0 Arend van Spriel 2011-10-05 347 static uint _dma_ctrlflags(struct dma_info *di, uint mask, uint flags)
> 5b435de0 Arend van Spriel 2011-10-05 348 {
> ae8e4672 Arend van Spriel 2011-10-29 349 uint dmactrlflags;
> 5b435de0 Arend van Spriel 2011-10-05 350
> 5b435de0 Arend van Spriel 2011-10-05 351 if (di == NULL) {
> 90123e04 Seth Forshee 2012-11-15 @352 brcms_dbg_dma(di->core, "NULL dma handle\n");
> 5b435de0 Arend van Spriel 2011-10-05 353 return 0;
> 5b435de0 Arend van Spriel 2011-10-05 354 }

Hi Fengguang,

Yep, that's obviously wrong. Thanks for the bug report.

John, here's a fix. There's no way to have a debug message if di is
NULL, so I've just removed it. Obviously I've never hitting that
condition anyway.

Seth

>From b0d7b62345e5b32b4022278f238296f5bdf06e8a Mon Sep 17 00:00:00 2001
From: Seth Forshee <seth.forshee@canonical.com>
Date: Thu, 29 Nov 2012 07:36:00 -0600
Subject: [PATCH] brcmsmac: Fix possible NULL pointer dereference in
_dma_ctrlflags()

There's a debug message to warn if this function is passed a NULL
pointer, but in order to print the message we have to dereference the
pointer. Obviously this isn't a good idea, so remove the message.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
---
drivers/net/wireless/brcm80211/brcmsmac/dma.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/net/wireless/brcm80211/brcmsmac/dma.c b/drivers/net/wireless/brcm80211/brcmsmac/dma.c
index 511e457..1860c57 100644
--- a/drivers/net/wireless/brcm80211/brcmsmac/dma.c
+++ b/drivers/net/wireless/brcm80211/brcmsmac/dma.c
@@ -349,10 +349,8 @@ static uint _dma_ctrlflags(struct dma_info *di, uint mask, uint flags)
{
uint dmactrlflags;

- if (di == NULL) {
- brcms_dbg_dma(di->core, "NULL dma handle\n");
+ if (di == NULL)
return 0;
- }

dmactrlflags = di->dma.dmactrlflags;
dmactrlflags &= ~mask;
--
1.7.9.5