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tcp: return sizeof tcp_dctcp_info in dctcp_get_info()

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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 <ncardwell@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Neal Cardwell 2016-06-13 11:20:35 -04:00 committed by David S. Miller
parent a5e27d18fe
commit dcf1158b27
1 changed files with 2 additions and 2 deletions
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4
net/ipv4/tcp_dctcp.c
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@ -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;
}