This is a note to let you know that I've just added the patch titled sctp: fail if no bound addresses can be used for a given scope to the 5.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: sctp-fail-if-no-bound-addresses-can-be-used-for-a-gi.patch and it can be found in the queue-5.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 7a56badcd3299789e740f8679935ba106c944202 Author: Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx> Date: Mon Jan 23 14:59:33 2023 -0300 sctp: fail if no bound addresses can be used for a given scope [ Upstream commit 458e279f861d3f61796894cd158b780765a1569f ] 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 <borrello@xxxxxxxxxxxxxxxx> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx> Reviewed-by: Xin Long <lucien.xin@xxxxxxxxx> Link: https://lore.kernel.org/r/9fcd182f1099f86c6661f3717f63712ddd1c676c.1674496737.git.marcelo.leitner@xxxxxxxxx Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/net/sctp/bind_addr.c b/net/sctp/bind_addr.c index 59e653b528b1..6b95d3ba8fe1 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);