From dcf1158b275f9d51d6a742cf7166edc764ee4718 Mon Sep 17 00:00:00 2001 From: Neal Cardwell Date: Mon, 13 Jun 2016 11:20:35 -0400 Subject: [PATCH] tcp: return sizeof tcp_dctcp_info in dctcp_get_info() Make sure that dctcp_get_info() returns only the size of the info->dctcp struct that it zeroes out and fills in. Previously it had been returning the size of the enclosing tcp_cc_info union, sizeof(*info). There is no problem yet, but that union that may one day be larger than struct tcp_dctcp_info, in which case the TCP_CC_INFO code might accidentally copy uninitialized bytes from the stack. Signed-off-by: Neal Cardwell Signed-off-by: Soheil Hassas Yeganeh Signed-off-by: Eric Dumazet Acked-by: Daniel Borkmann Signed-off-by: David S. Miller --- net/ipv4/tcp_dctcp.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/ipv4/tcp_dctcp.c b/net/ipv4/tcp_dctcp.c index 7e538f71f5fb..10d728b6804c 100644 --- a/net/ipv4/tcp_dctcp.c +++ b/net/ipv4/tcp_dctcp.c @@ -293,7 +293,7 @@ static size_t dctcp_get_info(struct sock *sk, u32 ext, int *attr, */ if (ext & (1 << (INET_DIAG_DCTCPINFO - 1)) || ext & (1 << (INET_DIAG_VEGASINFO - 1))) { - memset(info, 0, sizeof(struct tcp_dctcp_info)); + memset(&info->dctcp, 0, sizeof(info->dctcp)); if (inet_csk(sk)->icsk_ca_ops != &dctcp_reno) { info->dctcp.dctcp_enabled = 1; info->dctcp.dctcp_ce_state = (u16) ca->ce_state; @@ -303,7 +303,7 @@ static size_t dctcp_get_info(struct sock *sk, u32 ext, int *attr, } *attr = INET_DIAG_DCTCPINFO; - return sizeof(*info); + return sizeof(info->dctcp); } return 0; } -- 2.20.1