netdev - Re: [PATCH bpf-next v7 2/6] net/smc: fix UAF on smcsk after smc_listen

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]
Message-ID: <437f3824-f6be-4053-acfe-7f3f1ebc626c@linux.alibaba.com>
Date: Thu, 23 Jan 2025 10:21:46 +0800
From: Guangguan Wang <guangguan.wang@...ux.alibaba.com>
To: "D. Wythe" <alibuda@...ux.alibaba.com>, kgraul@...ux.ibm.com,
 wenjia@...ux.ibm.com, jaka@...ux.ibm.com, ast@...nel.org,
 daniel@...earbox.net, andrii@...nel.org, martin.lau@...ux.dev,
 pabeni@...hat.com, song@...nel.org, sdf@...gle.com, haoluo@...gle.com,
 yhs@...com, edumazet@...gle.com, john.fastabend@...il.com,
 kpsingh@...nel.org, jolsa@...nel.org, guwen@...ux.alibaba.com
Cc: kuba@...nel.org, davem@...emloft.net, netdev@...r.kernel.org,
 linux-s390@...r.kernel.org, linux-rdma@...r.kernel.org, bpf@...r.kernel.org
Subject: Re: [PATCH bpf-next v7 2/6] net/smc: fix UAF on smcsk after
 smc_listen_out()



On 2025/1/23 09:59, D. Wythe wrote:
> BPF CI testing report a UAF issue:
> 
>   [   16.446633] BUG: kernel NULL pointer dereference, address: 000000000000003  0
>   [   16.447134] #PF: supervisor read access in kernel mod  e
>   [   16.447516] #PF: error_code(0x0000) - not-present pag  e
>   [   16.447878] PGD 0 P4D   0
>   [   16.448063] Oops: Oops: 0000 [#1] PREEMPT SMP NOPT  I
>   [   16.448409] CPU: 0 UID: 0 PID: 9 Comm: kworker/0:1 Tainted: G           OE      6.13.0-rc3-g89e8a75fda73-dirty #4  2
>   [   16.449124] Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODUL  E
>   [   16.449502] Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/201  4
>   [   16.450201] Workqueue: smc_hs_wq smc_listen_wor  k
>   [   16.450531] RIP: 0010:smc_listen_work+0xc02/0x159  0
>   [   16.452158] RSP: 0018:ffffb5ab40053d98 EFLAGS: 0001024  6
>   [   16.452526] RAX: 0000000000000001 RBX: 0000000000000002 RCX: 000000000000030  0
>   [   16.452994] RDX: 0000000000000280 RSI: 00003513840053f0 RDI: 000000000000000  0
>   [   16.453492] RBP: ffffa097808e3800 R08: ffffa09782dba1e0 R09: 000000000000000  5
>   [   16.453987] R10: 0000000000000000 R11: 0000000000000000 R12: ffffa0978274640  0
>   [   16.454497] R13: 0000000000000000 R14: 0000000000000000 R15: ffffa09782d4092  0
>   [   16.454996] FS:  0000000000000000(0000) GS:ffffa097bbc00000(0000) knlGS:000000000000000  0
>   [   16.455557] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003  3
>   [   16.455961] CR2: 0000000000000030 CR3: 0000000102788004 CR4: 0000000000770ef  0
>   [   16.456459] PKRU: 5555555  4
>   [   16.456654] Call Trace  :
>   [   16.456832]  <TASK  >
>   [   16.456989]  ? __die+0x23/0x7  0
>   [   16.457215]  ? page_fault_oops+0x180/0x4c  0
>   [   16.457508]  ? __lock_acquire+0x3e6/0x249  0
>   [   16.457801]  ? exc_page_fault+0x68/0x20  0
>   [   16.458080]  ? asm_exc_page_fault+0x26/0x3  0
>   [   16.458389]  ? smc_listen_work+0xc02/0x159  0
>   [   16.458689]  ? smc_listen_work+0xc02/0x159  0
>   [   16.458987]  ? lock_is_held_type+0x8f/0x10  0
>   [   16.459284]  process_one_work+0x1ea/0x6d  0
>   [   16.459570]  worker_thread+0x1c3/0x38  0
>   [   16.459839]  ? __pfx_worker_thread+0x10/0x1  0
>   [   16.460144]  kthread+0xe0/0x11  0
>   [   16.460372]  ? __pfx_kthread+0x10/0x1  0
>   [   16.460640]  ret_from_fork+0x31/0x5  0
>   [   16.460896]  ? __pfx_kthread+0x10/0x1  0
>   [   16.461166]  ret_from_fork_asm+0x1a/0x3  0
>   [   16.461453]  </TASK  >
>   [   16.461616] Modules linked in: bpf_testmod(OE) [last unloaded: bpf_testmod(OE)  ]
>   [   16.462134] CR2: 000000000000003  0
>   [   16.462380] ---[ end trace 0000000000000000 ]---
>   [   16.462710] RIP: 0010:smc_listen_work+0xc02/0x1590
> 
> The direct cause of this issue is that after smc_listen_out_connected(),
> newclcsock->sk may be NULL since it will releases the smcsk. Therefore,
> if the application closes the socket immediately after accept,
> newclcsock->sk can be NULL. A possible execution order could be as
> follows:
> 
> smc_listen_work                                 | userspace
> -----------------------------------------------------------------
> lock_sock(sk)                                   |
> smc_listen_out_connected()                      |
> | \- smc_listen_out                             |
> |    | \- release_sock                          |
>      | |- sk->sk_data_ready()                   |
>                                                 | fd = accept();
>                                                 | close(fd);
>                                                 |  \- socket->sk = NULL;
> /* newclcsock->sk is NULL now */
> SMC_STAT_SERV_SUCC_INC(sock_net(newclcsock->sk))
> 
> Since smc_listen_out_connected() will not fail, simply swapping the order
> of the code can easily fix this issue.
> 
> Fixes: 3b2dec2603d5 ("net/smc: restructure client and server code in af_smc")
> Signed-off-by: D. Wythe <alibuda@...ux.alibaba.com>
> ---
>  net/smc/af_smc.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
> index c370efcfe3e8..9eebf7d0179e 100644
> --- a/net/smc/af_smc.c
> +++ b/net/smc/af_smc.c
> @@ -2549,8 +2549,9 @@ static void smc_listen_work(struct work_struct *work)
>  			goto out_decl;
>  	}
>  
> -	smc_listen_out_connected(new_smc);
>  	SMC_STAT_SERV_SUCC_INC(sock_net(newclcsock->sk), ini);
> +	/* smc_listen_out() will release smcsk */
> +	smc_listen_out_connected(new_smc);
>  	goto out_free;
>  
>  out_unlock:

LGTM.
Reviewed-by: Guangguan Wang <guangguan.wang@...ux.alibaba.com>