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sctp: add a ceiling to optlen in some sockopts

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Hangbin Liu reported that some sockopt calls could cause the kernel to log
a warning on memory allocation failure if the user supplied a large optlen
value. That is because some of them called memdup_user() without a ceiling
on optlen, allowing it to try to allocate really large buffers.

This patch adds a ceiling by limiting optlen to the maximum allowed that
would still make sense for these sockopt.

Reported-by: Hangbin Liu <haliu@redhat.com>
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Marcelo Ricardo Leitner 2018-01-08 19:02:28 -02:00 committed by David S. Miller
parent 2e83acb970
commit 5960cefab9
1 changed files with 10 additions and 0 deletions
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10
net/sctp/socket.c
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@ -3498,6 +3498,8 @@ static int sctp_setsockopt_hmac_ident(struct sock *sk,
if (optlen < sizeof(struct sctp_hmacalgo))
return -EINVAL;
optlen = min_t(unsigned int, optlen, sizeof(struct sctp_hmacalgo) +
SCTP_AUTH_NUM_HMACS * sizeof(u16));
hmacs = memdup_user(optval, optlen);
if (IS_ERR(hmacs))
@ -3536,6 +3538,11 @@ static int sctp_setsockopt_auth_key(struct sock *sk,
if (optlen <= sizeof(struct sctp_authkey))
return -EINVAL;
/* authkey->sca_keylength is u16, so optlen can't be bigger than
* this.
*/
optlen = min_t(unsigned int, optlen, USHRT_MAX +
sizeof(struct sctp_authkey));
authkey = memdup_user(optval, optlen);
if (IS_ERR(authkey))
@ -3893,6 +3900,9 @@ static int sctp_setsockopt_reset_streams(struct sock *sk,
if (optlen < sizeof(*params))
return -EINVAL;
/* srs_number_streams is u16, so optlen can't be bigger than this. */
optlen = min_t(unsigned int, optlen, USHRT_MAX +
sizeof(__u16) * sizeof(*params));
params = memdup_user(optval, optlen);
if (IS_ERR(params))