Re: [tipc-discussion] [PATCH] net: tipc: Fix a possible null-pointer dereference in tipc_publ_purge()

[David Miller]

From: Jia-Ju Bai 
Date: Thu, 25 Jul 2019 17:20:21 +0800

> @@ -223,7 +223,8 @@ static void tipc_publ_purge(struct net *net, struct 
> publication *publ, u32 addr)
>  publ->key);
>   }
>  
> - kfree_rcu(p, rcu);
> + if (p)
> + kfree_rcu(p, rcu);

Please fix your automated tools if that is what found this, because as
others have nodes kfree_rcu() can take a NULL pointer argument just
fine.

Thank you.


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Re: [tipc-discussion] [PATCH] net: tipc: Fix a possible null-pointer dereference in tipc_publ_purge()

[Ying Xue]

On 7/25/19 5:20 PM, Jia-Ju Bai wrote:
> In tipc_publ_purge(), there is an if statement on 215 to 
> check whether p is NULL: 
> if (p)
> 
> When p is NULL, it is used on line 226:
> kfree_rcu(p, rcu);
> 
> Thus, a possible null-pointer dereference may occur.
> 
> To fix this bug, p is checked before being used.
> 
> This bug is found by a static analysis tool STCheck written by us.
> 
> Signed-off-by: Jia-Ju Bai 
> ---
>  net/tipc/name_distr.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/net/tipc/name_distr.c b/net/tipc/name_distr.c
> index 44abc8e9c990..241ed2274473 100644
> --- a/net/tipc/name_distr.c
> +++ b/net/tipc/name_distr.c
> @@ -223,7 +223,8 @@ static void tipc_publ_purge(struct net *net, struct 
> publication *publ, u32 addr)
>  publ->key);
>   }
>  
> - kfree_rcu(p, rcu);
> + if (p)

No, I don't think so because kfree_rcu() will internally check if "p"
pointer is NULL or not.

> + kfree_rcu(p, rcu);
>  }
>  
>  /**
> 


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