If the previous list_for_each_entry_continue_rcu() don't exit early (no goto hit inside the loop), the iterator 'cvif' after the loop will be a bogus pointer to an invalid structure object containing the HEAD (&ar->vif_list). As a result, the use of 'cvif' after that will lead to a invalid memory access (i.e., 'cvif->id': the invalid pointer dereference when return back to/after the callsite in the carl9170_update_beacon()).
The original intention should have been to return the valid 'cvif' when found in list, NULL otherwise. So just return NULL when no entry found, to fix this bug.
Cc: stable@vger.kernel.org Fixes: 1f1d9654e183c ("carl9170: refactor carl9170_update_beacon") Signed-off-by: Xiaomeng Tong xiam0nd.tong@gmail.com ---
changes since v1: - just return NULL when no entry found (Christian Lamparter)
v1:https://lore.kernel.org/lkml/20220327072947.10744-1-xiam0nd.tong@gmail.com/
--- drivers/net/wireless/ath/carl9170/tx.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/drivers/net/wireless/ath/carl9170/tx.c b/drivers/net/wireless/ath/carl9170/tx.c index 1b76f4434c06..791f9f120af3 100644 --- a/drivers/net/wireless/ath/carl9170/tx.c +++ b/drivers/net/wireless/ath/carl9170/tx.c @@ -1558,6 +1558,9 @@ static struct carl9170_vif_info *carl9170_pick_beaconing_vif(struct ar9170 *ar) goto out; } } while (ar->beacon_enabled && i--); + + /* no entry found in list */ + return NULL; }
out: