Re: [PATCH net,v4] net/smc: prevent NULL pointer dereference in txopt_get

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On 8/15/24 11:15 AM, Jeongjun Park wrote:
2024년 8월 15일 (목) 오전 11:51, D. Wythe <alibuda@xxxxxxxxxxxxxxxxx>님이 작성:


On 8/14/24 11:05 PM, Jeongjun Park wrote:
Alexandra Winter wrote:
On 14.08.24 15:11, D. Wythe wrote:
      struct smc_sock {                /* smc sock container */
-    struct sock        sk;
+    union {
+        struct sock        sk;
+        struct inet_sock    inet;
+    };
I don't see a path where this breaks, but it looks risky to me.
Is an smc_sock always an inet_sock as well? Then can't you go with smc_sock->inet_sock->sk ?
Or only in the IPPROTO SMC case, and in the AF_SMC case it is not an inet_sock?

There is no smc_sock->inet_sock->sk before. And this part here was to
make smc_sock also
be an inet_sock.

For IPPROTO_SMC, smc_sock should be an inet_sock, but it is not before.
So, the initialization of certain fields
in smc_sock(for example, clcsk) will overwrite modifications made to the
inet_sock part in inet(6)_create.

For AF_SMC,  the only problem is that  some space will be wasted. Since
AF_SMC don't care the inet_sock part.
However, make the use of sock by AF_SMC and IPPROTO_SMC separately for
the sake of avoid wasting some space
is a little bit extreme.

Okay. I think using inet_sock instead of sock is also a good idea, but I
understand for now.

However, for some reason this patch status has become Changes Requested
, so we will split the patch into two and resend the v5 patch.

Regards,
Jeongjun Park

Why so hurry ? Are you rushing for some tasks ? Please be patient.

The discussion is still ongoing, and you need to wait for everyone's opinions, at least you can wait a few days to see if there are any other opinions, even if you think
your patch is correct.

There is no need to send a new patch. If this patch is approved, the net maintainer will handle it,
regardless of whether it is a change request or not.

And your new patch, I don't want to go too far, as you are a newcomer, I appreciate your report and
willingness to fix this issue. But it's wrong.

If you want to split them, embedding inet_sock should be the first patch, which is a basic logical issue.

Then, don't send patches so frequently, I'm very worried that you will immediately send out v6 after
seeing it.

Best wishes,
D. Wythe

hmm... then how about changing it to something like this?

@@ -283,7 +283,7 @@ struct smc_connection {
   };

   struct smc_sock {                           /* smc sock container */
-     struct sock             sk;
+     struct inet_sock        inet;
       struct socket           *clcsock;       /* internal tcp socket */
       void                    (*clcsk_state_change)(struct sock *sk);

Don't.

                                               /* original stat_change fct. */
@@ -327,7 +327,7 @@ struct smc_sock {                         /* smc sock container */
                                                * */
   };

-#define smc_sk(ptr) container_of_const(ptr, struct smc_sock, sk)
+#define smc_sk(ptr) container_of_const(ptr, struct smc_sock, inet.sk)

   static inline void smc_init_saved_callbacks(struct smc_sock *smc)
   {

It is definitely not normal to make the first member of smc_sock as sock.

Therefore, I think it would be appropriate to modify it to use inet_sock
as the first member like other protocols (sctp, dccp) and access sk in a
way like &smc->inet.sk.

Although this fix would require more code changes, we tested the bug and
confirmed that it was not triggered and the functionality was working
normally.

What do you think?

Regards,
Jeongjun Park





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