diff mbox

[wireless-next] brcmsmac: avoid 512 byte stack variable

Message ID 1360268032-52414-1-git-send-email-tim.gardner@canonical.com
State Not Applicable, archived
Delegated to: David Miller
Headers show

Commit Message

Tim Gardner Feb. 7, 2013, 8:13 p.m. UTC
Dynamically allocate the probe response template which
avoids potential stack corruption. Observed with smatch:

drivers/net/wireless/brcm80211/brcmsmac/main.c:7412 brcms_c_bss_update_probe_resp()
 warn: 'prb_resp' puts 512 bytes on stack

Cc: Brett Rudley <brudley@broadcom.com>
Cc: Arend van Spriel <arend@broadcom.com>
Cc: "Franky (Zhenhui) Lin" <frankyl@broadcom.com>
Cc: Hante Meuleman <meuleman@broadcom.com>
Cc: "John W. Linville" <linville@tuxdriver.com>
Cc: Seth Forshee <seth.forshee@canonical.com>
Cc: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Cc: Hauke Mehrtens <hauke@hauke-m.de>
Cc: linux-wireless@vger.kernel.org
Cc: brcm80211-dev-list@broadcom.com
Cc: netdev@vger.kernel.org
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
---
 drivers/net/wireless/brcm80211/brcmsmac/main.c |   11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

Comments

Joe Perches Feb. 7, 2013, 8:19 p.m. UTC | #1
On Thu, 2013-02-07 at 13:13 -0700, Tim Gardner wrote:
> Dynamically allocate the probe response template which
> avoids potential stack corruption. Observed with smatch:

trivial:

> diff --git a/drivers/net/wireless/brcm80211/brcmsmac/main.c b/drivers/net/wireless/brcm80211/brcmsmac/main.c
[]
> @@ -7408,9 +7408,16 @@ brcms_c_bss_update_probe_resp(struct brcms_c_info *wlc,
[]
> +	prb_resp = kmalloc(BCN_TMPL_LEN, GFP_ATOMIC);
> +	if (!prb_resp) {
> +		wiphy_err(wlc->wiphy, "wl: %s: failed to alloc %u bytes\n",
> +			__func__, BCN_TMPL_LEN);

Please remove the error message.
alloc's don't need specific OOM messages.

The mm subsystem already provides a standardized
message with a dump_stack().


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Arend van Spriel Feb. 7, 2013, 8:22 p.m. UTC | #2
On 02/07/2013 09:13 PM, Tim Gardner wrote:
> Dynamically allocate the probe response template which
> avoids potential stack corruption. Observed with smatch:
> 
> drivers/net/wireless/brcm80211/brcmsmac/main.c:7412 brcms_c_bss_update_probe_resp()
>  warn: 'prb_resp' puts 512 bytes on stack
> 
> Cc: Brett Rudley <brudley@broadcom.com>
> Cc: Arend van Spriel <arend@broadcom.com>
> Cc: "Franky (Zhenhui) Lin" <frankyl@broadcom.com>
> Cc: Hante Meuleman <meuleman@broadcom.com>
> Cc: "John W. Linville" <linville@tuxdriver.com>
> Cc: Seth Forshee <seth.forshee@canonical.com>
> Cc: Pieter-Paul Giesberts <pieterpg@broadcom.com>
> Cc: Hauke Mehrtens <hauke@hauke-m.de>
> Cc: linux-wireless@vger.kernel.org
> Cc: brcm80211-dev-list@broadcom.com
> Cc: netdev@vger.kernel.org

One comment below. When taken care of feel free to add:

Acked-by: Arend van Spriel <arend@broadcom.com>
> Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
> ---
>  drivers/net/wireless/brcm80211/brcmsmac/main.c |   11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/brcm80211/brcmsmac/main.c b/drivers/net/wireless/brcm80211/brcmsmac/main.c
> index c26992a..e392e76 100644
> --- a/drivers/net/wireless/brcm80211/brcmsmac/main.c
> +++ b/drivers/net/wireless/brcm80211/brcmsmac/main.c
> @@ -7408,9 +7408,16 @@ brcms_c_bss_update_probe_resp(struct brcms_c_info *wlc,
>  			      struct brcms_bss_cfg *cfg,
>  			      bool suspend)
>  {
> -	u16 prb_resp[BCN_TMPL_LEN / 2];
> +	u16 *prb_resp;
>  	int len = BCN_TMPL_LEN;
>  
> +	prb_resp = kmalloc(BCN_TMPL_LEN, GFP_ATOMIC);
> +	if (!prb_resp) {
> +		wiphy_err(wlc->wiphy, "wl: %s: failed to alloc %u bytes\n",
> +			__func__, BCN_TMPL_LEN);

I believe the kmalloc() call spews enough info upon allocation failure
so please remove the error message here.

> +		return;
> +	}
> +
>  	/*
>  	 * write the probe response to hardware, or save in
>  	 * the config structure
> @@ -7444,6 +7451,8 @@ brcms_c_bss_update_probe_resp(struct brcms_c_info *wlc,
>  
>  	if (suspend)
>  		brcms_c_enable_mac(wlc);
> +
> +	kfree(prb_resp);
>  }
>  
>  void brcms_c_update_probe_resp(struct brcms_c_info *wlc, bool suspend)
> 


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Arend van Spriel Feb. 7, 2013, 8:23 p.m. UTC | #3
On 02/07/2013 09:19 PM, Joe Perches wrote:
> On Thu, 2013-02-07 at 13:13 -0700, Tim Gardner wrote:
>> Dynamically allocate the probe response template which
>> avoids potential stack corruption. Observed with smatch:
> 
> trivial:
> 
>> diff --git a/drivers/net/wireless/brcm80211/brcmsmac/main.c b/drivers/net/wireless/brcm80211/brcmsmac/main.c
> []
>> @@ -7408,9 +7408,16 @@ brcms_c_bss_update_probe_resp(struct brcms_c_info *wlc,
> []
>> +	prb_resp = kmalloc(BCN_TMPL_LEN, GFP_ATOMIC);
>> +	if (!prb_resp) {
>> +		wiphy_err(wlc->wiphy, "wl: %s: failed to alloc %u bytes\n",
>> +			__func__, BCN_TMPL_LEN);
> 
> Please remove the error message.
> alloc's don't need specific OOM messages.
> 
> The mm subsystem already provides a standardized
> message with a dump_stack().

You beat me to the finish line :-)

Gr. AvS


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diff mbox

Patch

diff --git a/drivers/net/wireless/brcm80211/brcmsmac/main.c b/drivers/net/wireless/brcm80211/brcmsmac/main.c
index c26992a..e392e76 100644
--- a/drivers/net/wireless/brcm80211/brcmsmac/main.c
+++ b/drivers/net/wireless/brcm80211/brcmsmac/main.c
@@ -7408,9 +7408,16 @@  brcms_c_bss_update_probe_resp(struct brcms_c_info *wlc,
 			      struct brcms_bss_cfg *cfg,
 			      bool suspend)
 {
-	u16 prb_resp[BCN_TMPL_LEN / 2];
+	u16 *prb_resp;
 	int len = BCN_TMPL_LEN;
 
+	prb_resp = kmalloc(BCN_TMPL_LEN, GFP_ATOMIC);
+	if (!prb_resp) {
+		wiphy_err(wlc->wiphy, "wl: %s: failed to alloc %u bytes\n",
+			__func__, BCN_TMPL_LEN);
+		return;
+	}
+
 	/*
 	 * write the probe response to hardware, or save in
 	 * the config structure
@@ -7444,6 +7451,8 @@  brcms_c_bss_update_probe_resp(struct brcms_c_info *wlc,
 
 	if (suspend)
 		brcms_c_enable_mac(wlc);
+
+	kfree(prb_resp);
 }
 
 void brcms_c_update_probe_resp(struct brcms_c_info *wlc, bool suspend)