From: Lorenzo Bianconi <lorenzo@kernel•org>
To: Andrew Lunn <andrew+netdev@lunn•ch>,
"David S. Miller" <davem@davemloft•net>,
Eric Dumazet <edumazet@google•com>,
Jakub Kicinski <kuba@kernel•org>,
Paolo Abeni <pabeni@redhat•com>, Felix Fietkau <nbd@nbd•name>,
Matthias Brugger <matthias.bgg@gmail•com>,
AngeloGioacchino Del Regno
<angelogioacchino.delregno@collabora•com>
Cc: Florian Westphal <fw@strlen•de>,
linux-arm-kernel@lists•infradead.org,
linux-mediatek@lists•infradead.org, netdev@vger•kernel.org,
Lorenzo Bianconi <lorenzo@kernel•org>
Subject: [PATCH net 2/2] net: ethernet: mtk_eth_soc: Fix use-after-free in metadata dst teardown
Date: Tue, 02 Jun 2026 11:21:05 +0200 [thread overview]
Message-ID: <20260602-airoha-mtk-metadata-uaf-fix-v1-2-3aaa99d83351@kernel.org> (raw)
In-Reply-To: <20260602-airoha-mtk-metadata-uaf-fix-v1-0-3aaa99d83351@kernel.org>
mtk_free_dev() calls metadata_dst_free() which frees the metadata_dst
with kfree() immediately, bypassing the RCU grace period.
In the RX path, skb_dst_set_noref() sets a non-refcounted pointer from
the skb to the metadata_dst. This function requires RCU read-side
protection and the dst must remain valid until all RCU readers complete.
Since metadata_dst_free() calls kfree() directly, a use-after-free can
occur if any skb still holds a noref pointer to the dst when the driver
tears it down.
Replace metadata_dst_free() with dst_release() which properly goes
through the refcount path: when the refcount drops to zero, it schedules
the actual free via call_rcu_hurry(), ensuring all RCU readers have
completed before the memory is freed.
Fixes: 2d7605a72906 ("net: ethernet: mtk_eth_soc: enable hardware DSA untagging")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel•org>
---
drivers/net/ethernet/mediatek/mtk_eth_soc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index 8d225bc9f063..7d771168b990 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -4491,7 +4491,7 @@ static int mtk_free_dev(struct mtk_eth *eth)
for (i = 0; i < ARRAY_SIZE(eth->dsa_meta); i++) {
if (!eth->dsa_meta[i])
break;
- metadata_dst_free(eth->dsa_meta[i]);
+ dst_release(ð->dsa_meta[i]->dst);
}
return 0;
--
2.54.0
next prev parent reply other threads:[~2026-06-02 9:21 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-02 9:21 [PATCH net 0/2] Fix use-after-free in metadata dst teardown in airoha_eth and mtk_eth_soc drivers Lorenzo Bianconi
2026-06-02 9:21 ` [PATCH net 1/2] net: airoha: Fix use-after-free in metadata dst teardown Lorenzo Bianconi
2026-06-04 17:38 ` Jacob Keller
2026-06-04 21:23 ` Lorenzo Bianconi
2026-06-04 21:53 ` Jacob Keller
2026-06-02 9:21 ` Lorenzo Bianconi [this message]
2026-06-04 2:30 ` [PATCH net 0/2] Fix use-after-free in metadata dst teardown in airoha_eth and mtk_eth_soc drivers patchwork-bot+netdevbpf
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