From bf5c2d483b1302e81f4f4b9874229875da2eb562 Mon Sep 17 00:00:00 2001 From: Maxim Mikityanskiy Date: Thu, 12 May 2022 12:18:30 +0300 Subject: [PATCH] tls: Fix context leak on tls_device_down The commit cited below claims to fix a use-after-free condition after tls_device_down. Apparently, the description wasn't fully accurate. The context stayed alive, but ctx->netdev became NULL, and the offload was torn down without a proper fallback, so a bug was present, but a different kind of bug. Due to misunderstanding of the issue, the original patch dropped the refcount_dec_and_test line for the context to avoid the alleged premature deallocation. That line has to be restored, because it matches the refcount_inc_not_zero from the same function, otherwise the contexts that survived tls_device_down are leaked. This patch fixes the described issue by restoring refcount_dec_and_test. After this change, there is no leak anymore, and the fallback to software kTLS still works. Fixes: 77886d834bc2 ("net/tls: Fix use-after-free after the TLS device goes down and up") Signed-off-by: Maxim Mikityanskiy Reviewed-by: Tariq Toukan Link: https://lore.kernel.org/r/20220512091830.678684-1-maximmi@nvidia.com Signed-off-by: Jakub Kicinski --- net/tls/tls_device.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/tls/tls_device.c b/net/tls/tls_device.c index af875ad4a822d..3919fe2c58c5c 100644 --- a/net/tls/tls_device.c +++ b/net/tls/tls_device.c @@ -1347,7 +1347,10 @@ static int tls_device_down(struct net_device *netdev) /* Device contexts for RX and TX will be freed in on sk_destruct * 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)) + tls_device_free_ctx(ctx); } up_write(&device_offload_lock); -- 2.39.5