Eugene Teo wrote:
> Vlad Yasevich wrote:
>> The structure used for SCTP_AUTH_KEY option contains a
>> length that needs to be verfied to prevent buffer overflow
>> conditions. Spoted by Eugene Teo <eteo@xxxxxxxxxx>.
>>
>> Signed-off-by: Vlad Yasevich <vladislav.yasevich@xxxxxx>
>> ---
>> net/sctp/auth.c | 4 ++++
>> net/sctp/socket.c | 5 +++++
>> 2 files changed, 9 insertions(+), 0 deletions(-)
>>
>> diff --git a/net/sctp/auth.c b/net/sctp/auth.c
>> index 675a5c3..1fcb4cf 100644
>> --- a/net/sctp/auth.c
>> +++ b/net/sctp/auth.c
>> @@ -80,6 +80,10 @@ static struct sctp_auth_bytes *sctp_auth_create_key(__u32 key_len, gfp_t gfp)
>
> This should be __u16 key_len.
>
>> {
>> struct sctp_auth_bytes *key;
>>
>> + /* Verify that we are not going to overflow INT_MAX */
>> + if ((INT_MAX - key_len) < sizeof(struct sctp_auth_bytes))
>> + return NULL;
>
> Shouldn't this be UINT_MAX? But then if you are going to change
> sctp_auth_create_key() to accept __u16 key_len, then it should be
> USHORT_MAX.
>
I'd rather keep it a u32 since this function is not only for userspace,
but for creating a generated key.
Yes, UINT_MAX makes more sense.
>> /* Allocate the shared key */
>> key = kmalloc(sizeof(struct sctp_auth_bytes) + key_len, gfp);
>> if (!key)
>> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
>> index bb5c9ef..afa952e 100644
>> --- a/net/sctp/socket.c
>> +++ b/net/sctp/socket.c
>> @@ -3144,6 +3144,11 @@ static int sctp_setsockopt_auth_key(struct sock *sk,
>> goto out;
>> }
>>
>> + if (authkey->sca_keylength > optlen) {
>> + ret = -EINVAL;
>> + goto out;
>
> Is there a better upper bound check?
Hm... optlen - sizeof(struct sctp_authkey) is more accurate.
There is really no other bound.
-vlad
>
>> asoc = sctp_id2assoc(sk, authkey->sca_assoc_id);
>> if (!asoc && authkey->sca_assoc_id && sctp_style(sk, UDP)) {
>> ret = -EINVAL;
>
> Thanks,
> Eugene
>
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