Re: [PATCH] mac80211: mlme: check for null after calling kmemdup
From: Johannes Berg <johannes@sipsolutions.net>
Date: 2022-01-04 14:00:53
Also in:
linux-wireless, lkml
On Fri, 2021-12-31 at 18:03 +0800, Jiasheng Jiang wrote:
As the possible failure of the alloc, the ifmgd->assoc_req_ies might be NULL pointer and will be used by cfg80211_rx_assoc_resp() with the wrong length. Therefore it might be better to set length to 0 if fails as same as ieee80211_mgd_stop().
That feels a bit vague, and indeed I cannot find any place that would actually dereference the pointer if it's NULL? Still maybe a good as a cleanup.
quoted hunk ↗ jump to hunk
Fixes: 4d9ec73d2b78 ("cfg80211: Report Association Request frame IEs in association events") Signed-off-by: Jiasheng Jiang <redacted> --- net/mac80211/mlme.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c index 9bed6464c5bd..258b492c699c 100644 --- a/net/mac80211/mlme.c +++ b/net/mac80211/mlme.c@@ -1058,7 +1058,10 @@ 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); - ifmgd->assoc_req_ies_len = pos - ie_start; + if (!ifmgd->assoc_req_ies) + ifmgd->assoc_req_ies_len = 0; + else + ifmgd->assoc_req_ies_len = pos - ie_start;
But it seems it would be better to actually fail the association in this case? There's a reason we're reporting this, so that we can see HT/VHT/..., and I'm sure that will be necessary in many cases. johannes