[PATCH net-next v2] mptcp: correct MPTCP_SUBFLOW_ATTR_SSN_OFFSET reserved size

[Eugene Syromiatnikov <esyr@redhat.com>]

ssn_offset field is u32 and is placed into the netlink response with
nla_put_u32(), but only 2 bytes are reserved for the attribute payload
in subflow_get_info_size() (even though it makes no difference
in the end, as it is aligned up to 4 bytes).  Supply the correct
argument to the relevant nla_total_size() call to make it less
confusing.

Fixes: 5147dfb50832 ("mptcp: allow dumping subflow context to userspace")
Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com>
---
v2:
  - Added prefix to the patch subject
  - Fixed commit message formatting (line width, "Fixes:" commit hash
    prefix size)
v1: https://lore.kernel.org/mptcp/20240809094321.GA8122@asgard.redhat.com/
---
 net/mptcp/diag.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/mptcp/diag.c b/net/mptcp/diag.c
index 3ae46b545d2c..2d3efb405437 100644
--- a/net/mptcp/diag.c
+++ b/net/mptcp/diag.c
@@ -94,7 +94,7 @@ static size_t subflow_get_info_size(const struct sock *sk)
 		nla_total_size(4) +	/* MPTCP_SUBFLOW_ATTR_RELWRITE_SEQ */
 		nla_total_size_64bit(8) +	/* MPTCP_SUBFLOW_ATTR_MAP_SEQ */
 		nla_total_size(4) +	/* MPTCP_SUBFLOW_ATTR_MAP_SFSEQ */
-		nla_total_size(2) +	/* MPTCP_SUBFLOW_ATTR_SSN_OFFSET */
+		nla_total_size(4) +	/* MPTCP_SUBFLOW_ATTR_SSN_OFFSET */
 		nla_total_size(2) +	/* MPTCP_SUBFLOW_ATTR_MAP_DATALEN */
 		nla_total_size(4) +	/* MPTCP_SUBFLOW_ATTR_FLAGS */
 		nla_total_size(1) +	/* MPTCP_SUBFLOW_ATTR_ID_REM */
-- 
2.28.0