rxrpc: Fix use-after-free in rxrpc_receive_data()
The subpacket scanning loop in rxrpc_receive_data() references the subpacket count in the private data part of the sk_buff in the loop termination condition. However, when the final subpacket is pasted into the ring buffer, the function is no longer has a ref on the sk_buff and should not be looking at sp->* any more. This point is actually marked in the code when skb is cleared (but sp is not - which is an error). Fix this by caching sp->nr_subpackets in a local variable and using that instead. Also clear 'sp' to catch accesses after that point. This can show up as an oops in rxrpc_get_skb() if sp->nr_subpackets gets trashed by the sk_buff getting freed and reused in the meantime. Fixes: e2de6c40 ("rxrpc: Use info in skbuff instead of reparsing a jumbo packet") Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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