3.5.7.23 -stable review patch. If anyone has any objections, please let me know.
------------------ From: Daniel Borkmann <[email protected]> commit 88362ad8f9a6cea787420b57cc27ccacef000dbe upstream. This was originally reported in [1] and posted by Neil Horman [2], he said: Fix up a missed null pointer check in the asconf code. If we don't find a local address, but we pass in an address length of more than 1, we may dereference a NULL laddr pointer. Currently this can't happen, as the only users of the function pass in the value 1 as the addrcnt parameter, but its not hot path, and it doesn't hurt to check for NULL should that ever be the case. The callpath from sctp_asconf_mgmt() looks okay. But this could be triggered from sctp_setsockopt_bindx() call with SCTP_BINDX_REM_ADDR and addrcnt > 1 while passing all possible addresses from the bind list to SCTP_BINDX_REM_ADDR so that we do *not* find a single address in the association's bind address list that is not in the packed array of addresses. If this happens when we have an established association with ASCONF-capable peers, then we could get a NULL pointer dereference as we only check for laddr == NULL && addrcnt == 1 and call later sctp_make_asconf_update_ip() with NULL laddr. BUT: this actually won't happen as sctp_bindx_rem() will catch such a case and return with an error earlier. As this is incredably unintuitive and error prone, add a check to catch at least future bugs here. As Neil says, its not hot path. Introduced by 8a07eb0a5 ("sctp: Add ASCONF operation on the single-homed host"). [1] http://www.spinics.net/lists/linux-sctp/msg02132.html [2] http://www.spinics.net/lists/linux-sctp/msg02133.html Reported-by: Dan Carpenter <[email protected]> Signed-off-by: Neil Horman <[email protected]> Signed-off-by: Daniel Borkmann <[email protected]> Cc: Michio Honda <[email protected]> Acked-By: Neil Horman <[email protected]> Acked-by: Vlad Yasevich <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Luis Henriques <[email protected]> --- net/sctp/socket.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/sctp/socket.c b/net/sctp/socket.c index 7e40284..d01802a 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -814,6 +814,9 @@ static int sctp_send_asconf_del_ip(struct sock *sk, goto skip_mkasconf; } + if (laddr == NULL) + return -EINVAL; + /* We do not need RCU protection throughout this loop * because this is done under a socket lock from the * setsockopt call. -- 1.8.3.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
