Re: [PATCH net,v3] net/smc: prevent NULL pointer dereference in txopt_get

["D. Wythe" <alibuda@linux.alibaba.com>]

On 8/14/24 10:25 AM, D. Wythe wrote:
>
>
> On 8/13/24 7:48 PM, Jeongjun Park wrote:
>> D. Wythe wrote:
>>>
>>>
>>> On 8/13/24 6:07 PM, Jeongjun Park wrote:
>>>> Since smc_inet6_prot does not initialize ipv6_pinfo_offset, 
>>>> inet6_create()
>>>> copies an incorrect address value, sk + 0 (offset), to 
>>>> inet_sk(sk)->pinet6.
>>>>
>>>> In addition, since inet_sk(sk)->pinet6 and smc_sk(sk)->clcsock 
>>>> practically
>>>> point to the same address, when smc_create_clcsk() stores the newly
>>>> created clcsock in smc_sk(sk)->clcsock, inet_sk(sk)->pinet6 is 
>>>> corrupted
>>>> into clcsock. This causes NULL pointer dereference and various other
>>>> memory corruptions.
>>>>
>>>> To solve this, we need to add a smc6_sock structure for 
>>>> ipv6_pinfo_offset
>>>> initialization and modify the smc_sock structure.
>>>>
>>>> Reported-by: syzbot+f69bfae0a4eb29976e44@syzkaller.appspotmail.com
>>>> Tested-by: syzbot+f69bfae0a4eb29976e44@syzkaller.appspotmail.com
>>>> Fixes: d25a92ccae6b ("net/smc: Introduce IPPROTO_SMC")
>>>> Signed-off-by: Jeongjun Park <aha310510@gmail.com>
>>>> ---
>>>>    net/smc/smc.h      | 19 ++++++++++---------
>>>>    net/smc/smc_inet.c | 24 +++++++++++++++---------
>>>>    2 files changed, 25 insertions(+), 18 deletions(-)
>>>>
>>>> diff --git a/net/smc/smc.h b/net/smc/smc.h
>>>> index 34b781e463c4..f4d9338b5ed5 100644
>>>> --- a/net/smc/smc.h
>>>> +++ b/net/smc/smc.h
>>>> @@ -284,15 +284,6 @@ struct smc_connection {
>>>>
>>>>    struct smc_sock {                           /* smc sock 
>>>> container */
>>>>        struct sock             sk;
>>>> -     struct socket           *clcsock;       /* internal tcp 
>>>> socket */
>>>> -     void                    (*clcsk_state_change)(struct sock *sk);
>>>> -                                             /* original 
>>>> stat_change fct. */
>>>> -     void                    (*clcsk_data_ready)(struct sock *sk);
>>>> -                                             /* original 
>>>> data_ready fct. */
>>>> -     void                    (*clcsk_write_space)(struct sock *sk);
>>>> -                                             /* original 
>>>> write_space fct. */
>>>> -     void                    (*clcsk_error_report)(struct sock *sk);
>>>> -                                             /* original 
>>>> error_report fct. */
>>>>        struct smc_connection   conn;           /* smc connection */
>>>>        struct smc_sock         *listen_smc;    /* listen parent */
>>>>        struct work_struct      connect_work;   /* handle 
>>>> non-blocking connect*/
>>>> @@ -325,6 +316,16 @@ struct smc_sock 
>>>> {                                /* smc sock container */
>>>>                                                /* protects clcsock 
>>>> of a listen
>>>>                                                 * socket
>>>>                                                 * */
>>>> +     struct socket           *clcsock;       /* internal tcp 
>>>> socket */
>>>> +     void                    (*clcsk_state_change)(struct sock *sk);
>>>> +                                             /* original 
>>>> stat_change fct. */
>>>> +     void                    (*clcsk_data_ready)(struct sock *sk);
>>>> +                                             /* original 
>>>> data_ready fct. */
>>>> +     void                    (*clcsk_write_space)(struct sock *sk);
>>>> +                                             /* original 
>>>> write_space fct. */
>>>> +     void                    (*clcsk_error_report)(struct sock *sk);
>>>> +                                             /* original 
>>>> error_report fct. */
>>>> +
>>>>    };
>>>>
>>>>    #define smc_sk(ptr) container_of_const(ptr, struct smc_sock, sk)
>>>> diff --git a/net/smc/smc_inet.c b/net/smc/smc_inet.c
>>>> index bece346dd8e9..25f34fd65e8d 100644
>>>> --- a/net/smc/smc_inet.c
>>>> +++ b/net/smc/smc_inet.c
>>>> @@ -60,16 +60,22 @@ static struct inet_protosw smc_inet_protosw = {
>>>>    };
>>>>
>>>>    #if IS_ENABLED(CONFIG_IPV6)
>>>> +struct smc6_sock {
>>>> +     struct smc_sock smc;
>>>> +     struct ipv6_pinfo np;
>>>> +};
>>> I prefer to:
>>>
>>> struct ipv6_pinfo inet6;
>> Okay, I'll write a v4 patch and send it to you tomorrow.
>>
>> Regards,
>> Jeongjun Park
>
> Before you issue the v4, I still don't know why you move clcsk_xxx 
> from smc_connection
> to smc_sock, can you explain it ?


I misread it, it seems you're moving them from head to tail, but still, 
the same question,
why move it ?

Thanks
D. Wythe


>
> Also, regarding alignment, it's okay for me whether it's aligned or 
> not，But I checked the styles of other types of
> structures and did not strictly require alignment, so I now feel that 
> there is no need to
> modify so much to do alignment.
>
> D. Wythe



>
>>
>>>> +
>>>>    static struct proto smc_inet6_prot = {
>>>> -     .name           = "INET6_SMC",
>>>> -     .owner          = THIS_MODULE,
>>>> -     .init           = smc_inet_init_sock,
>>>> -     .hash           = smc_hash_sk,
>>>> -     .unhash         = smc_unhash_sk,
>>>> -     .release_cb     = smc_release_cb,
>>>> -     .obj_size       = sizeof(struct smc_sock),
>>>> -     .h.smc_hash     = &smc_v6_hashinfo,
>>>> -     .slab_flags     = SLAB_TYPESAFE_BY_RCU,
>>>> +     .name                           = "INET6_SMC",
>>>> +     .owner                          = THIS_MODULE,
>>>> +     .init                           = smc_inet_init_sock,
>>>> +     .hash                           = smc_hash_sk,
>>>> +     .unhash                         = smc_unhash_sk,
>>>> +     .release_cb                     = smc_release_cb,
>>>> +     .obj_size                       = sizeof(struct smc6_sock),
>>>> +     .h.smc_hash                     = &smc_v6_hashinfo,
>>>> +     .slab_flags                     = SLAB_TYPESAFE_BY_RCU,
>>>> +     .ipv6_pinfo_offset              = offsetof(struct smc6_sock, 
>>>> np),
>>>>    };
>>>>
>>>>    static const struct proto_ops smc_inet6_stream_ops = {
>>>> -- 
>