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Date:   Sun, 11 Aug 2019 21:29:28 -0700 (PDT)
Message-Id: <20190811.212928.1681769879219779999.davem@davemloft.net>
To:     dhowells@redhat.com
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        linux-afs@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH net] rxrpc: Fix local refcounting
From:   David Miller <davem@davemloft.net>
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From: David Howells <dhowells@redhat.com>
Date: Fri, 09 Aug 2019 22:47:47 +0100

> Fix rxrpc_unuse_local() to handle a NULL local pointer as it can be called
> on an unbound socket on which rx->local is not yet set.
> 
> The following reproduced (includes omitted):
> 
> 	int main(void)
> 	{
> 		socket(AF_RXRPC, SOCK_DGRAM, AF_INET);
> 		return 0;
> 	}
> 
> causes the following oops to occur:
> 
> 	BUG: kernel NULL pointer dereference, address: 0000000000000010
> 	...
> 	RIP: 0010:rxrpc_unuse_local+0x8/0x1b
> 	...
> 	Call Trace:
> 	 rxrpc_release+0x2b5/0x338
> 	 __sock_release+0x37/0xa1
> 	 sock_close+0x14/0x17
> 	 __fput+0x115/0x1e9
> 	 task_work_run+0x72/0x98
> 	 do_exit+0x51b/0xa7a
> 	 ? __context_tracking_exit+0x4e/0x10e
> 	 do_group_exit+0xab/0xab
> 	 __x64_sys_exit_group+0x14/0x17
> 	 do_syscall_64+0x89/0x1d4
> 	 entry_SYSCALL_64_after_hwframe+0x49/0xbe
> 
> Reported-by: syzbot+20dee719a2e090427b5f@syzkaller.appspotmail.com
> Fixes: 730c5fd42c1e ("rxrpc: Fix local endpoint refcounting")
> Signed-off-by: David Howells <dhowells@redhat.com>
> cc: Jeffrey Altman <jaltman@auristor.com>

Applied.