Hangbin Liu reported that some sockopt calls could cause the kernel to log a warning on memory allocation failure if the user supplied a large optlen value. That is because some of them called memdup_user() without a ceiling on optlen, allowing it to try to allocate really large buffers. This patch adds a ceiling by limiting optlen to the maximum allowed that would still make sense for these sockopt. Reported-by: Hangbin Liu <haliu@xxxxxxxxxx> Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx> --- net/sctp/socket.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/net/sctp/socket.c b/net/sctp/socket.c index 54c046783a89e76c9909ee85c83e6be38ada41a7..022b94f11fd8ac0d3b839b16dfc14f86abf2324f 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -3498,6 +3498,8 @@ static int sctp_setsockopt_hmac_ident(struct sock *sk, if (optlen < sizeof(struct sctp_hmacalgo)) return -EINVAL; + optlen = min_t(unsigned int, optlen, sizeof(struct sctp_hmacalgo) + + SCTP_AUTH_NUM_HMACS * sizeof(u16)); hmacs = memdup_user(optval, optlen); if (IS_ERR(hmacs)) @@ -3536,6 +3538,11 @@ static int sctp_setsockopt_auth_key(struct sock *sk, if (optlen <= sizeof(struct sctp_authkey)) return -EINVAL; + /* authkey->sca_keylength is u16, so optlen can't be bigger than + * this. + */ + optlen = min_t(unsigned int, optlen, USHRT_MAX + + sizeof(struct sctp_authkey)); authkey = memdup_user(optval, optlen); if (IS_ERR(authkey)) @@ -3893,6 +3900,9 @@ static int sctp_setsockopt_reset_streams(struct sock *sk, if (optlen < sizeof(*params)) return -EINVAL; + /* srs_number_streams is u16, so optlen can't be bigger than this. */ + optlen = min_t(unsigned int, optlen, USHRT_MAX + + sizeof(__u16) * sizeof(*params)); params = memdup_user(optval, optlen); if (IS_ERR(params)) -- 2.14.3 -- To unsubscribe from this list: send the line "unsubscribe linux-sctp" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
