2012-12-06 20:49:05

by Tim Gardner

Subject: [PATCH wireless-next] iwlwifi: iwlagn_request_scan: Fix check for NULL priv->scan_request

The WARN_ON_ONCE() check for scan_request will not correctly detect
a NULL pointer for scan_type == IWL_SCAN_NORMAL. Make it explicit
that the check only applies to normal scans.

Convert WARN_ON_ONCE to WARN_ON since priv->scan_request really _can't_
be NULL for normal scans. If it is then we should emit frequent warnings.

This smatch warning led to scrutiny of iwlagn_request_scan():

drivers/net/wireless/iwlwifi/dvm/scan.c:894 iwlagn_request_scan() error: we previously assumed 'priv->scan_request' could be null (see line 792)

Cc: Johannes Berg <[email protected]>
Cc: Wey-Yi Guy <[email protected]>
Cc: Intel Linux Wireless <[email protected]>
Cc: "John W. Linville" <[email protected]>
Cc: Emmanuel Grumbach <[email protected]>
Cc: Don Fry <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Tim Gardner <[email protected]>
---

This patch does apply to 3.6.y, but it doesn't fix an existing
bug so I don't think it qualifies. This patch simply makes
the driver more robust for future development.

drivers/net/wireless/iwlwifi/dvm/scan.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/iwlwifi/dvm/scan.c b/drivers/net/wireless/iwlwifi/dvm/scan.c
index bb9f625..e5cbcca 100644
--- a/drivers/net/wireless/iwlwifi/dvm/scan.c
+++ b/drivers/net/wireless/iwlwifi/dvm/scan.c
@@ -673,8 +673,9 @@ static int iwlagn_request_scan(struct iwl_priv *priv, struct ieee80211_vif *vif)
const u8 *ssid = NULL;
u8 ssid_len = 0;

- if (WARN_ON_ONCE(priv->scan_request &&
- priv->scan_request->n_channels > MAX_SCAN_CHANNEL))
+ if (WARN_ON(priv->scan_type == IWL_SCAN_NORMAL &&
+ (!priv->scan_request ||
+ priv->scan_request->n_channels > MAX_SCAN_CHANNEL)))
return -EINVAL;

lockdep_assert_held(&priv->mutex);
--
1.7.9.5

2012-12-07 13:28:55

by Tim Gardner

Subject: [PATCH V2 wireless-next] iwlwifi: iwlagn_request_scan: Fix check for priv->scan_request

The WARN_ON_ONCE() check for scan_request will not correctly detect
a NULL pointer for scan_type == IWL_SCAN_NORMAL. Make it explicit
that the check only applies to normal scans.

Convert WARN_ON_ONCE to WARN_ON since priv->scan_request really _can't_
be NULL for normal scans. If it is then we should emit frequent warnings.

This smatch warning led to scrutiny of iwlagn_request_scan():

drivers/net/wireless/iwlwifi/dvm/scan.c:894 iwlagn_request_scan() error: we previously assumed 'priv->scan_request' could be null (see line 792)

Cc: Johannes Berg <[email protected]>
Cc: Wey-Yi Guy <[email protected]>
Cc: Intel Linux Wireless <[email protected]>
Cc: "John W. Linville" <[email protected]>
Cc: Emmanuel Grumbach <[email protected]>
Cc: Don Fry <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Tim Gardner <[email protected]>
---

This patch does apply to 3.6.y, but it doesn't fix an existing
bug so I don't think it qualifies. This patch simply makes
the driver more robust for future development.

V2 - corrected indentation more like the rest of the source
in this file.

drivers/net/wireless/iwlwifi/dvm/scan.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/iwlwifi/dvm/scan.c b/drivers/net/wireless/iwlwifi/dvm/scan.c
index bb9f625..fe91c5a 100644
--- a/drivers/net/wireless/iwlwifi/dvm/scan.c
+++ b/drivers/net/wireless/iwlwifi/dvm/scan.c
@@ -673,8 +673,9 @@ static int iwlagn_request_scan(struct iwl_priv *priv, struct ieee80211_vif *vif)
const u8 *ssid = NULL;
u8 ssid_len = 0;

- if (WARN_ON_ONCE(priv->scan_request &&
- priv->scan_request->n_channels > MAX_SCAN_CHANNEL))
+ if (WARN_ON(priv->scan_type == IWL_SCAN_NORMAL &&
+ (!priv->scan_request ||
+ priv->scan_request->n_channels > MAX_SCAN_CHANNEL)))
return -EINVAL;

lockdep_assert_held(&priv->mutex);
--
1.7.9.5

2012-12-07 16:05:36

by Johannes Berg

Subject: Re: [PATCH V2 wireless-next] iwlwifi: iwlagn_request_scan: Fix check for priv->scan_request

On Fri, 2012-12-07 at 06:28 -0700, Tim Gardner wrote:
> The WARN_ON_ONCE() check for scan_request will not correctly detect
> a NULL pointer for scan_type == IWL_SCAN_NORMAL. Make it explicit
> that the check only applies to normal scans.
>
> Convert WARN_ON_ONCE to WARN_ON since priv->scan_request really _can't_
> be NULL for normal scans. If it is then we should emit frequent warnings.
>
> This smatch warning led to scrutiny of iwlagn_request_scan():
>
> drivers/net/wireless/iwlwifi/dvm/scan.c:894 iwlagn_request_scan() error: we previously assumed 'priv->scan_request' could be null (see line 792)
>
> Cc: Johannes Berg <[email protected]>
> Cc: Wey-Yi Guy <[email protected]>
> Cc: Intel Linux Wireless <[email protected]>
> Cc: "John W. Linville" <[email protected]>
> Cc: Emmanuel Grumbach <[email protected]>
> Cc: Don Fry <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Signed-off-by: Tim Gardner <[email protected]>
> ---
>
> This patch does apply to 3.6.y, but it doesn't fix an existing
> bug so I don't think it qualifies. This patch simply makes
> the driver more robust for future development.
>
> V2 - corrected indentation more like the rest of the source
> in this file.

Thanks, I've picked it up now, adding one space in the condition
still :)
It's in my internal tree for now, so it'll be a few days until it
trickles out to iwlwifi-next.

johannes

2012-12-06 21:41:39

by Johannes Berg

Subject: Re: [PATCH wireless-next] iwlwifi: iwlagn_request_scan: Fix check for NULL priv->scan_request

> --- a/drivers/net/wireless/iwlwifi/dvm/scan.c
> +++ b/drivers/net/wireless/iwlwifi/dvm/scan.c
> @@ -673,8 +673,9 @@ static int iwlagn_request_scan(struct iwl_priv *priv, struct ieee80211_vif *vif)
> const u8 *ssid = NULL;
> u8 ssid_len = 0;
>
> - if (WARN_ON_ONCE(priv->scan_request &&
> - priv->scan_request->n_channels > MAX_SCAN_CHANNEL))
> + if (WARN_ON(priv->scan_type == IWL_SCAN_NORMAL &&
> + (!priv->scan_request ||
> + priv->scan_request->n_channels > MAX_SCAN_CHANNEL)))
> return -EINVAL;

I'll pick it up if you fix the indentation :P

johannes