2022-01-05 01:33:39

by Jiasheng Jiang

Subject: [PATCH v2] mac80211: mlme: check for null after calling kmemdup

As the possible failure of the alloc, the ifmgd->assoc_req_ies might be
NULL pointer returned from kmemdup().
Therefore it might be better to free the skb and return in order to fail
the association, like ieee80211_assoc_success().

Fixes: 4d9ec73d2b78 ("cfg80211: Report Association Request frame IEs in association events")
Signed-off-by: Jiasheng Jiang <[email protected]>
---
v2: Change to fail the association if kmemdup returns NULL.
---
net/mac80211/mlme.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 9bed6464c5bd..b5dfdf953286 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -1058,6 +1058,11 @@ static void ieee80211_send_assoc(struct ieee80211_sub_if_data *sdata)
pos = skb_tail_pointer(skb);
kfree(ifmgd->assoc_req_ies);
ifmgd->assoc_req_ies = kmemdup(ie_start, pos - ie_start, GFP_ATOMIC);
+ if (!ifmgd->assoc_req_ies) {
+ dev_kfree_skb(skb);
+ return;
+ }
+
ifmgd->assoc_req_ies_len = pos - ie_start;

drv_mgd_prepare_tx(local, sdata, 0);
--
2.25.1

2022-01-05 07:49:38

by Johannes Berg

Subject: Re: [PATCH v2] mac80211: mlme: check for null after calling kmemdup

On Wed, 2022-01-05 at 09:33 +0800, Jiasheng Jiang wrote:
> As the possible failure of the alloc, the ifmgd->assoc_req_ies might be
> NULL pointer returned from kmemdup().
> Therefore it might be better to free the skb and return in order to fail
> the association, like ieee80211_assoc_success().
>
> Fixes: 4d9ec73d2b78 ("cfg80211: Report Association Request frame IEs in association events")
> Signed-off-by: Jiasheng Jiang <[email protected]>
> ---
> v2: Change to fail the association if kmemdup returns NULL.
> ---
> net/mac80211/mlme.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
> index 9bed6464c5bd..b5dfdf953286 100644
> --- a/net/mac80211/mlme.c
> +++ b/net/mac80211/mlme.c
> @@ -1058,6 +1058,11 @@ static void ieee80211_send_assoc(struct ieee80211_sub_if_data *sdata)
> pos = skb_tail_pointer(skb);
> kfree(ifmgd->assoc_req_ies);
> ifmgd->assoc_req_ies = kmemdup(ie_start, pos - ie_start, GFP_ATOMIC);
> + if (!ifmgd->assoc_req_ies) {
> + dev_kfree_skb(skb);
> + return;
> + }
>

That doesn't fail, that just doesn't send the frame and will then time
out later, not very useful?

johannes