netdev - Re: [tipc-discussion] [net v3 1/1] tipc: fix memory leak caused by tipc_buf

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: <CAM_iQpU-tu39476eh_22rcNaZt8EJ3FeQJu82J4p6L26vnKcxQ@mail.gmail.com>
Date:   Wed, 28 Oct 2020 12:31:30 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Tung Nguyen <tung.q.nguyen@...tech.com.au>
Cc:     David Miller <davem@...emloft.net>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        tipc-discussion@...ts.sourceforge.net
Subject: Re: [tipc-discussion] [net v3 1/1] tipc: fix memory leak caused by tipc_buf_append()

On Tue, Oct 27, 2020 at 1:09 PM Tung Nguyen
<tung.q.nguyen@...tech.com.au> wrote:
>
> Commit ed42989eab57 ("tipc: fix the skb_unshare() in tipc_buf_append()")
> replaced skb_unshare() with skb_copy() to not reduce the data reference
> counter of the original skb intentionally. This is not the correct

More precisely, it is shinfo->dataref.


> way to handle the cloned skb because it causes memory leak in 2
> following cases:
>  1/ Sending multicast messages via broadcast link
>   The original skb list is cloned to the local skb list for local
>   destination. After that, the data reference counter of each skb
>   in the original list has the value of 2. This causes each skb not
>   to be freed after receiving ACK:
>   tipc_link_advance_transmq()
>   {
>    ...
>    /* release skb */
>    __skb_unlink(skb, &l->transmq);
>    kfree_skb(skb); <-- memory exists after being freed
>   }
>
>  2/ Sending multicast messages via replicast link
>   Similar to the above case, each skb cannot be freed after purging
>   the skb list:
>   tipc_mcast_xmit()
>   {
>    ...
>    __skb_queue_purge(pkts); <-- memory exists after being freed
>   }
>
> This commit fixes this issue by using skb_unshare() instead. Besides,
> to avoid use-after-free error reported by KASAN, the pointer to the
> fragment is set to NULL before calling skb_unshare() to make sure that
> the original skb is not freed after freeing the fragment 2 times in
> case skb_unshare() returns NULL.
>
> Fixes: ed42989eab57 ("tipc: fix the skb_unshare() in tipc_buf_append()")
> Acked-by: Jon Maloy <jmaloy@...hat.com>
> Reported-by: Thang Hoang Ngo <thang.h.ngo@...tech.com.au>
> Signed-off-by: Tung Nguyen <tung.q.nguyen@...tech.com.au>

Acked-by: Cong Wang <xiyou.wangcong@...il.com>