Patch "mt76: fix a possible NULL pointer dereference in mt76_testmode_dump" has been added to the 5.9-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    mt76: fix a possible NULL pointer dereference in mt76_testmode_dump

to the 5.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     mt76-fix-a-possible-null-pointer-dereference-in-mt76.patch
and it can be found in the queue-5.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit fa6872117b9f6d769b1d7cd5c6abcafa58614f1d
Author: Lorenzo Bianconi <lorenzo@xxxxxxxxxx>
Date:   Fri Aug 21 12:52:15 2020 +0200

    mt76: fix a possible NULL pointer dereference in mt76_testmode_dump
    
    [ Upstream commit ce8463a726a5669b200a1c2c17f95bc1394cc6bf ]
    
    Fix a possible NULL pointer dereference in mt76_testmode_dump() since
    nla_nest_start returns NULL in case of error
    
    Fixes: f0efa8621550e ("mt76: add API for testmode support")
    Signed-off-by: Lorenzo Bianconi <lorenzo@xxxxxxxxxx>
    Signed-off-by: Felix Fietkau <nbd@xxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/net/wireless/mediatek/mt76/testmode.c b/drivers/net/wireless/mediatek/mt76/testmode.c
index 75bb02cdfdae4..5bd6ac1ba3b5b 100644
--- a/drivers/net/wireless/mediatek/mt76/testmode.c
+++ b/drivers/net/wireless/mediatek/mt76/testmode.c
@@ -442,9 +442,13 @@ int mt76_testmode_dump(struct ieee80211_hw *hw, struct sk_buff *msg,
 	mutex_lock(&dev->mutex);
 
 	if (tb[MT76_TM_ATTR_STATS]) {
+		err = -EINVAL;
+
 		a = nla_nest_start(msg, MT76_TM_ATTR_STATS);
-		err = mt76_testmode_dump_stats(dev, msg);
-		nla_nest_end(msg, a);
+		if (a) {
+			err = mt76_testmode_dump_stats(dev, msg);
+			nla_nest_end(msg, a);
+		}
 
 		goto out;
 	}