[PATCH V2] cfg80211: Fix possible memory leak in function cfg80211_bss_update

[PATCH V2] cfg80211: Fix possible memory leak in function cfg80211_bss_update

[Nguyen Dinh Phi]

When we exceed the limit of BSS entries, this function will free the
new entry, however, at this time, it is the last door to access the
inputed ies, so these ies will be unreferenced objects and cause memory
leak.
Therefore we should free its ies before deallocating the new entry, beside
of dropping it from hidden_list.

Signed-off-by: Nguyen Dinh Phi <phind.uet@gmail.com>
---
V2:	- Add subsystem to the subject line.
	- Use bss_ref_put function for better clean-up dynamically allocated
	cfg80211_internal_bss objects. It helps to clean relative hidden_bss.

 net/wireless/scan.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index f03c7ac8e184..7897b1478c3c 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -1754,16 +1754,14 @@ cfg80211_bss_update(struct cfg80211_registered_device *rdev,
 			 * be grouped with this beacon for updates ...
 			 */
 			if (!cfg80211_combine_bsses(rdev, new)) {
-				kfree(new);
+				bss_ref_put(rdev, new);
 				goto drop;
 			}
 		}

 		if (rdev->bss_entries >= bss_entries_limit &&
 		    !cfg80211_bss_expire_oldest(rdev)) {
-			if (!list_empty(&new->hidden_list))
-				list_del(&new->hidden_list);
-			kfree(new);
+			bss_ref_put(rdev, new);
 			goto drop;
 		}

--
2.25.1

Re: [PATCH V2] cfg80211: Fix possible memory leak in function cfg80211_bss_update

[Greg KH]

On Mon, Jun 28, 2021 at 09:23:34PM +0800, Nguyen Dinh Phi wrote:
> When we exceed the limit of BSS entries, this function will free the
> new entry, however, at this time, it is the last door to access the
> inputed ies, so these ies will be unreferenced objects and cause memory
> leak.
> Therefore we should free its ies before deallocating the new entry, beside
> of dropping it from hidden_list.
> 
> Signed-off-by: Nguyen Dinh Phi <phind.uet@gmail.com>
> ---
> V2:	- Add subsystem to the subject line.
> 	- Use bss_ref_put function for better clean-up dynamically allocated
> 	cfg80211_internal_bss objects. It helps to clean relative hidden_bss.
> 
>  net/wireless/scan.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/net/wireless/scan.c b/net/wireless/scan.c
> index f03c7ac8e184..7897b1478c3c 100644
> --- a/net/wireless/scan.c
> +++ b/net/wireless/scan.c
> @@ -1754,16 +1754,14 @@ cfg80211_bss_update(struct cfg80211_registered_device *rdev,
>  			 * be grouped with this beacon for updates ...
>  			 */
>  			if (!cfg80211_combine_bsses(rdev, new)) {
> -				kfree(new);
> +				bss_ref_put(rdev, new);
>  				goto drop;
>  			}
>  		}
> 
>  		if (rdev->bss_entries >= bss_entries_limit &&
>  		    !cfg80211_bss_expire_oldest(rdev)) {
> -			if (!list_empty(&new->hidden_list))
> -				list_del(&new->hidden_list);
> -			kfree(new);
> +			bss_ref_put(rdev, new);
>  			goto drop;
>  		}
> 
> --
> 2.25.1

Did this change get lost somewhere?

thanks,

greg k-h

Re: [PATCH V2] cfg80211: Fix possible memory leak in function cfg80211_bss_update

[Kalle Valo]

Greg KH <greg@kroah.com> writes:

> On Mon, Jun 28, 2021 at 09:23:34PM +0800, Nguyen Dinh Phi wrote:
>> When we exceed the limit of BSS entries, this function will free the
>> new entry, however, at this time, it is the last door to access the
>> inputed ies, so these ies will be unreferenced objects and cause memory
>> leak.
>> Therefore we should free its ies before deallocating the new entry, beside
>> of dropping it from hidden_list.
>> 
>> Signed-off-by: Nguyen Dinh Phi <phind.uet@gmail.com>

[...]

> Did this change get lost somewhere?

Johannes applied it to the macc80211 tree:

https://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211.git/commit/?id=f9a5c358c8d26fed0cc45f2afc64633d4ba21dff

Ah, and it's already in Linus' tree as well.

-- 
https://patchwork.kernel.org/project/linux-wireless/list/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

Re: [PATCH V2] cfg80211: Fix possible memory leak in function cfg80211_bss_update

[Greg KH]

On Sat, Jul 31, 2021 at 10:53:28AM +0300, Kalle Valo wrote:
> Greg KH <greg@kroah.com> writes:
> 
> > On Mon, Jun 28, 2021 at 09:23:34PM +0800, Nguyen Dinh Phi wrote:
> >> When we exceed the limit of BSS entries, this function will free the
> >> new entry, however, at this time, it is the last door to access the
> >> inputed ies, so these ies will be unreferenced objects and cause memory
> >> leak.
> >> Therefore we should free its ies before deallocating the new entry, beside
> >> of dropping it from hidden_list.
> >> 
> >> Signed-off-by: Nguyen Dinh Phi <phind.uet@gmail.com>
> 
> [...]
> 
> > Did this change get lost somewhere?
> 
> Johannes applied it to the macc80211 tree:
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211.git/commit/?id=f9a5c358c8d26fed0cc45f2afc64633d4ba21dff
> 
> Ah, and it's already in Linus' tree as well.

Ah, thanks, I had missed that it just landed there.

greg k-h