[PATCH 5.15 32/69] net/tls: Remove the context from the list in tls_device_down

Greg Kroah-Hartman
2022-08-01T12:03:44Z

From: Maxim Mikityanskiy <maximmi@nvidia.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@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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);