Re: [PATCH net-next 2/5] net/rxrpc: Use local FCrypt-PCBC implementation

[David Howells <dhowells@redhat.com>]

Eric Biggers <ebiggers@kernel.org> wrote:

> +	if (skb_linearize(skb) < 0)
> +		return -ENOMEM;

It seems skb_linearize() doesn't like being used in this fashion:

	kernel BUG at net/core/skbuff.c:2295!
	...
	RIP: 0010:pskb_expand_head+0x41/0x220
	 __pskb_pull_tail+0x5e/0x2f0
	 rxkad_verify_packet_2+0xa8/0x190
	 rxkad_verify_packet+0x12c/0x150
	 rxrpc_recvmsg_data+0x1b0/0x470
	 rxrpc_kernel_recv_data+0xa6/0x210
	 afs_extract_data+0x5e/0x180
	 yfs_deliver_fs_fetch_data64+0x10b/0x200
	 afs_deliver_to_call+0xea/0x440
	 afs_read_receive+0x8d/0x150
	 afs_fetch_data_async_rx+0x12/0x20
	 process_one_work+0x18e/0x2b0

which corresponds to this:

	BUG_ON(skb_shared(skb));

Presumably this is done because fcrypt_pcbc_decrypt() doesn't handle being
called on a split buffer.  I think this may require skb_copy() to be used
instead, but that would need to be handled in rxrpc_input_call_event().

I think rxkad_decrypt_response() should be okay because the encrypted data is
extracted into a buffer first before being decrypted.

David