Re: [PATCH] net/nfc: fix use-after-free llcp_sock_bind/connect

[Leon Romanovsky <leon@kernel.org>]

On Tue, May 04, 2021 at 07:10:10PM +0000, patchwork-bot+netdevbpf@kernel.org wrote:
> Hello:
> 
> This patch was applied to netdev/net.git (refs/heads/master):
> 
> On Tue,  4 May 2021 10:16:46 +0300 you wrote:
> > Commits 8a4cd82d ("nfc: fix refcount leak in llcp_sock_connect()")
> > and c33b1cc62 ("nfc: fix refcount leak in llcp_sock_bind()")
> > fixed a refcount leak bug in bind/connect but introduced a
> > use-after-free if the same local is assigned to 2 different sockets.
> > 
> > This can be triggered by the following simple program:
> >     int sock1 = socket( AF_NFC, SOCK_STREAM, NFC_SOCKPROTO_LLCP );
> >     int sock2 = socket( AF_NFC, SOCK_STREAM, NFC_SOCKPROTO_LLCP );
> >     memset( &addr, 0, sizeof(struct sockaddr_nfc_llcp) );
> >     addr.sa_family = AF_NFC;
> >     addr.nfc_protocol = NFC_PROTO_NFC_DEP;
> >     bind( sock1, (struct sockaddr*) &addr, sizeof(struct sockaddr_nfc_llcp) )
> >     bind( sock2, (struct sockaddr*) &addr, sizeof(struct sockaddr_nfc_llcp) )
> >     close(sock1);
> >     close(sock2);
> > 
> > [...]
> 
> Here is the summary with links:
>   - net/nfc: fix use-after-free llcp_sock_bind/connect
>     https://git.kernel.org/netdev/net/c/c61760e6940d

Dave,

Can you please share your thoughts how this patch can be correct?
https://lore.kernel.org/netdev/YJIjN6MTRdQ7Bvcp@unreal/T/#m1e67ae6c2658312a134f65819c5ad92511f207c1

It is also under review, so unclear why it was merged.

Thanks

> 
> You are awesome, thank you!
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