sctp: fix copying more bytes than expected in sctp_add_bind_addr

Dmitry reported that sctp_add_bind_addr may read more bytes than
expected in case the parameter is a IPv4 addr supplied by the user
through calls such as sctp_bindx_add(), because it always copies
sizeof(union sctp_addr) while the buffer may be just a struct
sockaddr_in, which is smaller.

This patch then fixes it by limiting the memcpy to the min between the
union size and a (new parameter) provided addr size. Where possible this
parameter still is the size of that union, except for reading from
user-provided buffers, which then it accounts for protocol type.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Tested-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 1 deletions

diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index 205630bb5010..f816344f65f2 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -1098,7 +1098,7 @@ int sctp_bind_addr_dup(struct sctp_bind_addr *dest,
 			const struct sctp_bind_addr *src,
 			gfp_t gfp);
 int sctp_add_bind_addr(struct sctp_bind_addr *, union sctp_addr *,
-		       __u8 addr_state, gfp_t gfp);
+		       int new_size, __u8 addr_state, gfp_t gfp);
 int sctp_del_bind_addr(struct sctp_bind_addr *, union sctp_addr *);
 int sctp_bind_addr_match(struct sctp_bind_addr *, const union sctp_addr *,
 			 struct sctp_sock *);