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Date: Sat, 17 Jul 2021 17:19:19 -0400 From: Xin Long <lucien.xin@...il.com> To: network dev <netdev@...r.kernel.org>, davem@...emloft.net, kuba@...nel.org, linux-sctp@...r.kernel.org Cc: Marcelo Ricardo Leitner <marcelo.leitner@...il.com> Subject: [PATCH net] sctp: trim optlen when it's a huge value in sctp_setsockopt After commit ca84bd058dae ("sctp: copy the optval from user space in sctp_setsockopt"), it does memory allocation in sctp_setsockopt with the optlen, and it would fail the allocation and return error if the optlen from user space is a huge value. This breaks some sockopts, like SCTP_HMAC_IDENT, SCTP_RESET_STREAMS and SCTP_AUTH_KEY, as when processing these sockopts before, optlen would be trimmed to a biggest value it needs when optlen is a huge value, instead of failing the allocation and returning error. This patch is to fix the allocation failure when it's a huge optlen from user space by trimming it to the biggest size sctp sockopt may need when necessary, and this biggest size is from sctp_setsockopt_reset_streams() for SCTP_RESET_STREAMS, which is bigger than those for SCTP_HMAC_IDENT and SCTP_AUTH_KEY. Fixes: ca84bd058dae ("sctp: copy the optval from user space in sctp_setsockopt") Signed-off-by: Xin Long <lucien.xin@...il.com> --- net/sctp/socket.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/sctp/socket.c b/net/sctp/socket.c index e64e01f61b11..6b937bfd4751 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -4577,6 +4577,10 @@ static int sctp_setsockopt(struct sock *sk, int level, int optname, } if (optlen > 0) { + /* Trim it to the biggest size sctp sockopt may need if necessary */ + optlen = min_t(unsigned int, optlen, + PAGE_ALIGN(USHRT_MAX + + sizeof(__u16) * sizeof(struct sctp_reset_streams))); kopt = memdup_sockptr(optval, optlen); if (IS_ERR(kopt)) return PTR_ERR(kopt); -- 2.27.0
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