netdev - Re: [RFC PATCH] net/tls: Fix skb memory leak when running kTLS traffic

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 7 Jan 2022 10:51:06 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     Eric Dumazet <edumazet@...gle.com>
Cc:     Gal Pressman <gal@...dia.com>,
        "David S. Miller" <davem@...emloft.net>, <netdev@...r.kernel.org>,
        Tariq Toukan <tariqt@...dia.com>,
        Saeed Mahameed <saeedm@...dia.com>
Subject: Re: [RFC PATCH] net/tls: Fix skb memory leak when running kTLS
 traffic

On Sun, 2 Jan 2022 10:12:53 +0200 Gal Pressman wrote:
> The cited Fixes commit introduced a memory leak when running kTLS
> traffic (with/without hardware offloads).
> I'm running nginx on the server side and wrk on the client side and get
> the following:
> 
>   unreferenced object 0xffff8881935e9b80 (size 224):
>   comm "softirq", pid 0, jiffies 4294903611 (age 43.204s)
>   hex dump (first 32 bytes):
>     80 9b d0 36 81 88 ff ff 00 00 00 00 00 00 00 00  ...6............
>     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>   backtrace:
>     [<00000000efe2a999>] build_skb+0x1f/0x170
>     [<00000000ef521785>] mlx5e_skb_from_cqe_mpwrq_linear+0x2bc/0x610 [mlx5_core]
>     [<00000000945d0ffe>] mlx5e_handle_rx_cqe_mpwrq+0x264/0x9e0 [mlx5_core]
>     [<00000000cb675b06>] mlx5e_poll_rx_cq+0x3ad/0x17a0 [mlx5_core]
>     [<0000000018aac6a9>] mlx5e_napi_poll+0x28c/0x1b60 [mlx5_core]
>     [<000000001f3369d1>] __napi_poll+0x9f/0x560
>     [<00000000cfa11f72>] net_rx_action+0x357/0xa60
>     [<000000008653b8d7>] __do_softirq+0x282/0x94e
>     [<00000000644923c6>] __irq_exit_rcu+0x11f/0x170
>     [<00000000d4085f8f>] irq_exit_rcu+0xa/0x20
>     [<00000000d412fef4>] common_interrupt+0x7d/0xa0
>     [<00000000bfb0cebc>] asm_common_interrupt+0x1e/0x40
>     [<00000000d80d0890>] default_idle+0x53/0x70
>     [<00000000f2b9780e>] default_idle_call+0x8c/0xd0
>     [<00000000c7659e15>] do_idle+0x394/0x450
> 
> I'm not familiar with these areas of the code, but I've added this
> sk_defer_free_flush() to tls_sw_recvmsg() based on a hunch and it
> resolved the issue.
> 
> Eric, do you think this is the correct fix? Maybe we're missing a call
> to sk_defer_free_flush() in other places as well?

Any thoughts, Eric? Since the merge window is coming soon should 
we purge the defer free queue when socket is destroyed at least?
All the .read_sock callers will otherwise risk the leaks, it seems.

> Fixes: f35f821935d8 ("tcp: defer skb freeing after socket lock is released")
> Signed-off-by: Gal Pressman <gal@...dia.com>
> ---
>  net/tls/tls_sw.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
> index 3f271e29812f..95e774f1b91f 100644
> --- a/net/tls/tls_sw.c
> +++ b/net/tls/tls_sw.c
> @@ -1990,6 +1990,7 @@ int tls_sw_recvmsg(struct sock *sk,
>  
>  end:
>  	release_sock(sk);
> +	sk_defer_free_flush(sk);
>  	if (psock)
>  		sk_psock_put(sk, psock);
>  	return copied ? : err;