linux-kernel - [PATCH 5.15 32/69] net/tls: Remove the context from the list in tls_device

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Message-Id: <20220801114135.810497549@linuxfoundation.org>
Date:   Mon,  1 Aug 2022 13:46:56 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Maxim Mikityanskiy <maximmi@...dia.com>,
        Tariq Toukan <tariqt@...dia.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 5.15 32/69] net/tls: Remove the context from the list in tls_device_down

From: Maxim Mikityanskiy <maximmi@...dia.com>

commit f6336724a4d4220c89a4ec38bca84b03b178b1a3 upstream.

tls_device_down takes a reference on all contexts it's going to move to
the degraded state (software fallback). If sk_destruct runs afterwards,
it can reduce the reference counter back to 1 and return early without
destroying the context. Then tls_device_down will release the reference
it took and call tls_device_free_ctx. However, the context will still
stay in tls_device_down_list forever. The list will contain an item,
memory for which is released, making a memory corruption possible.

Fix the above bug by properly removing the context from all lists before
any call to tls_device_free_ctx.

Fixes: 3740651bf7e2 ("tls: Fix context leak on tls_device_down")
Signed-off-by: Maxim Mikityanskiy <maximmi@...dia.com>
Reviewed-by: Tariq Toukan <tariqt@...dia.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/tls/tls_device.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/net/tls/tls_device.c
+++ b/net/tls/tls_device.c
@@ -1351,8 +1351,13 @@ static int tls_device_down(struct net_de
 		 * by tls_device_free_ctx. rx_conf and tx_conf stay in TLS_HW.
 		 * Now release the ref taken above.
 		 */
-		if (refcount_dec_and_test(&ctx->refcount))
+		if (refcount_dec_and_test(&ctx->refcount)) {
+			/* sk_destruct ran after tls_device_down took a ref, and
+			 * it returned early. Complete the destruction here.
+			 */
+			list_del(&ctx->list);
 			tls_device_free_ctx(ctx);
+		}
 	}
 
 	up_write(&device_offload_lock);