From: Marcelo Ricardo Leitner Date: Mon, 23 Jan 2023 17:59:33 +0000 (-0300) Subject: sctp: fail if no bound addresses can be used for a given scope X-Git-Tag: v6.6.7~3671^2~9 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=458e279f861d3f61796894cd158b780765a1569f;p=platform%2Fkernel%2Flinux-starfive.git sctp: fail if no bound addresses can be used for a given scope Currently, if you bind the socket to something like: servaddr.sin6_family = AF_INET6; servaddr.sin6_port = htons(0); servaddr.sin6_scope_id = 0; inet_pton(AF_INET6, "::1", &servaddr.sin6_addr); And then request a connect to: connaddr.sin6_family = AF_INET6; connaddr.sin6_port = htons(20000); connaddr.sin6_scope_id = if_nametoindex("lo"); inet_pton(AF_INET6, "fe88::1", &connaddr.sin6_addr); What the stack does is: - bind the socket - create a new asoc - to handle the connect - copy the addresses that can be used for the given scope - try to connect But the copy returns 0 addresses, and the effect is that it ends up trying to connect as if the socket wasn't bound, which is not the desired behavior. This unexpected behavior also allows KASLR leaks through SCTP diag interface. The fix here then is, if when trying to copy the addresses that can be used for the scope used in connect() it returns 0 addresses, bail out. This is what TCP does with a similar reproducer. Reported-by: Pietro Borrello Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Marcelo Ricardo Leitner Reviewed-by: Xin Long Link: https://lore.kernel.org/r/9fcd182f1099f86c6661f3717f63712ddd1c676c.1674496737.git.marcelo.leitner@gmail.com Signed-off-by: Jakub Kicinski --- diff --git a/net/sctp/bind_addr.c b/net/sctp/bind_addr.c index 59e653b..6b95d3b 100644 --- a/net/sctp/bind_addr.c +++ b/net/sctp/bind_addr.c @@ -73,6 +73,12 @@ int sctp_bind_addr_copy(struct net *net, struct sctp_bind_addr *dest, } } + /* If somehow no addresses were found that can be used with this + * scope, it's an error. + */ + if (list_empty(&dest->address_list)) + error = -ENETUNREACH; + out: if (error) sctp_bind_addr_clean(dest);