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@xxxxxxxxx>
---
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
