2020-04-25 13:13:02

by Xiyu Yang

Subject: [PATCH] net/tls: Fix sk_psock refcnt leak when in tls_data_ready()

tls_data_ready() invokes sk_psock_get(), which returns a reference of
the specified sk_psock object to "psock" with increased refcnt.

When tls_data_ready() returns, local variable "psock" becomes invalid,
so the refcount should be decreased to keep refcount balanced.

The reference counting issue happens in one exception handling path of
tls_data_ready(). When "psock->ingress_msg" is empty but "psock" is not
NULL, the function forgets to decrease the refcnt increased by
sk_psock_get(), causing a refcnt leak.

Fix this issue by calling sk_psock_put() on all paths when "psock" is
not NULL.

Signed-off-by: Xiyu Yang <[email protected]>
Signed-off-by: Xin Tan <[email protected]>
---
net/tls/tls_sw.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index c98e602a1a2d..4eef5617e033 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -2081,8 +2081,9 @@ static void tls_data_ready(struct sock *sk)
strp_data_ready(&ctx->strp);

psock = sk_psock_get(sk);
- if (psock && !list_empty(&psock->ingress_msg)) {
- ctx->saved_data_ready(sk);
+ if (psock) {
+ if (!list_empty(&psock->ingress_msg))
+ ctx->saved_data_ready(sk);
sk_psock_put(sk, psock);
}
}
--
2.7.4

2020-04-27 18:25:12

by David Miller

Subject: Re: [PATCH] net/tls: Fix sk_psock refcnt leak when in tls_data_ready()

From: Xiyu Yang <[email protected]>
Date: Sat, 25 Apr 2020 21:10:23 +0800

> tls_data_ready() invokes sk_psock_get(), which returns a reference of
> the specified sk_psock object to "psock" with increased refcnt.
>
> When tls_data_ready() returns, local variable "psock" becomes invalid,
> so the refcount should be decreased to keep refcount balanced.
>
> The reference counting issue happens in one exception handling path of
> tls_data_ready(). When "psock->ingress_msg" is empty but "psock" is not
> NULL, the function forgets to decrease the refcnt increased by
> sk_psock_get(), causing a refcnt leak.
>
> Fix this issue by calling sk_psock_put() on all paths when "psock" is
> not NULL.
>
> Signed-off-by: Xiyu Yang <[email protected]>
> Signed-off-by: Xin Tan <[email protected]>

Applied and queued up for -stable.