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sctp: trim optlen when it's a huge value in sctp_setsockopt

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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@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Xin Long 2021-07-17 17:19:19 -04:00 committed by David S. Miller
parent f5051bcece
commit 2f3fdd8d48
1 changed files with 4 additions and 0 deletions
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4
net/sctp/socket.c
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@ -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);