diff options
| author | Sven Eckelmann <sven@narfation.org> | 2026-05-06 23:20:51 +0300 |
|---|---|---|
| committer | Sven Eckelmann <sven@narfation.org> | 2026-05-08 15:28:56 +0300 |
| commit | cf6b604011591865ae39ac82de8978c1120d17af (patch) | |
| tree | 025b0f78e45e5788e56c569bf308568cd8a6ba74 | |
| parent | 4ae1709a314060a196981b344610d023ea841e57 (diff) | |
| download | linux-cf6b604011591865ae39ac82de8978c1120d17af.tar.xz | |
batman-adv: bla: only purge non-released claims
When batadv_bla_purge_claims() goes through the list of claims, it is only
traversing the hash list with an rcu_read_lock(). Due to a potential
parallel batadv_claim_put(), it can happen that it encounters a claim which
was actually in the process of being released+freed by
batadv_claim_release(). In this case, backbone_gw is set to NULL before the
delayed RCU kfree is started. Calling batadv_bla_claim_get_backbone_gw() is
then no longer allowed because it would cause a NULL-ptr derefence.
To avoid this, only claims with a valid reference counter must be purged.
All others are already taken care of.
Cc: stable@kernel.org
Fixes: 23721387c409 ("batman-adv: add basic bridge loop avoidance code")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
| -rw-r--r-- | net/batman-adv/bridge_loop_avoidance.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c index 8b77dd2ecfa4..879ab043d57a 100644 --- a/net/batman-adv/bridge_loop_avoidance.c +++ b/net/batman-adv/bridge_loop_avoidance.c @@ -1288,6 +1288,13 @@ static void batadv_bla_purge_claims(struct batadv_priv *bat_priv, rcu_read_lock(); hlist_for_each_entry_rcu(claim, head, hash_entry) { + /* only purge claims not currently in the process of being released. + * Such claims could otherwise have a NULL-ptr backbone_gw set because + * they already went through batadv_claim_release() + */ + if (!kref_get_unless_zero(&claim->refcount)) + continue; + backbone_gw = batadv_bla_claim_get_backbone_gw(claim); if (now) goto purge_now; @@ -1313,6 +1320,7 @@ purge_now: claim->addr, claim->vid); skip: batadv_backbone_gw_put(backbone_gw); + batadv_claim_put(claim); } rcu_read_unlock(); } |