2021-09-21 17:32 GMT+09:00, Ralph Boehme <slow@xxxxxxxxx>:
> Hi Namjae,
>
> thanks! One nitpick below.
>
> Am 19.09.21 um 04:13 schrieb Namjae Jeon:
>> From: Hyunchul Lee <hyc.lee@xxxxxxxxx>
>>
>> Add buffer validation for SMB2_CREATE_CONTEXT.
>>
>> Cc: Ronnie Sahlberg <ronniesahlberg@xxxxxxxxx>
>> Cc: Ralph Böhme <slow@xxxxxxxxx>
>> Cc: Steve French <smfrench@xxxxxxxxx>
>> Signed-off-by: Hyunchul Lee <hyc.lee@xxxxxxxxx>
>> Signed-off-by: Namjae Jeon <linkinjeon@xxxxxxxxxx>
>> ---
>> fs/ksmbd/oplock.c | 35 +++++++++++++++++++++++++----------
>> fs/ksmbd/smb2pdu.c | 25 ++++++++++++++++++++++++-
>> fs/ksmbd/smbacl.c | 9 ++++++++-
>> 3 files changed, 57 insertions(+), 12 deletions(-)
>>
>> diff --git a/fs/ksmbd/oplock.c b/fs/ksmbd/oplock.c
>> index 16b6236d1bd2..3fd2713f2282 100644
>> --- a/fs/ksmbd/oplock.c
>> +++ b/fs/ksmbd/oplock.c
>> @@ -1451,26 +1451,41 @@ struct lease_ctx_info *parse_lease_state(void
>> *open_req)
>> */
>> struct create_context *smb2_find_context_vals(void *open_req, const char
>> *tag)
>> {
>> - char *data_offset;
>> + struct smb2_create_req *req = (struct smb2_create_req *)open_req;
>> struct create_context *cc;
>> - unsigned int next = 0;
>> + char *data_offset, *data_end;
>> char *name;
>> - struct smb2_create_req *req = (struct smb2_create_req *)open_req;
>> + unsigned int next = 0;
>> + unsigned int name_off, name_len, value_off, value_len;
>>
>> data_offset = (char *)req + 4 +
>> le32_to_cpu(req->CreateContextsOffset);
>> + data_end = data_offset + le32_to_cpu(req->CreateContextsLength);
>> cc = (struct create_context *)data_offset;
>> do {
>> - int val;
>> -
>> cc = (struct create_context *)((char *)cc + next);
>> - name = le16_to_cpu(cc->NameOffset) + (char *)cc;
>> - val = le16_to_cpu(cc->NameLength);
>> - if (val < 4)
>> + if ((char *)cc + offsetof(struct create_context, Buffer) >
>> + data_end)
>> return ERR_PTR(-EINVAL);
>>
>> - if (memcmp(name, tag, val) == 0)
>> - return cc;
>> next = le32_to_cpu(cc->Next);
>> + name_off = le16_to_cpu(cc->NameOffset);
>> + name_len = le16_to_cpu(cc->NameLength);
>> + value_off = le16_to_cpu(cc->DataOffset);
>> + value_len = le32_to_cpu(cc->DataLength);
>> +
>> + if ((char *)cc + name_off + name_len > data_end ||
>> + (value_len && (char *)cc + value_off + value_len > data_end))
>> + return ERR_PTR(-EINVAL);
>> + else if (next && (next < name_off + name_len ||
>> + (value_len && next < value_off + value_len)))
>> + return ERR_PTR(-EINVAL);
>
> The else is a bit confusing and not needed. Also, Samba has a few
> additional checks, I wonder whether we should add those two:
>
> if ((next & 0x7) != 0 ||
> next > remaining ||
> name_offset != 16 ||
> name_length < 4 ||
> name_offset + name_length > remaining ||
> (data_offset & 0x7) != 0 ||
> (data_offset && (data_offset < name_offset +
> name_length)) ||
> (data_offset > remaining) ||
> (data_offset + (uint64_t)data_length > remaining)) {
> return NT_STATUS_INVALID_PARAMETER;
> }
I will fix it on v2.
Thank your review!
>
> Other then that lgtm.
>
> Thanks!
> -slow
>
> --
> Ralph Boehme, Samba Team https://samba.org/
> SerNet Samba Team Lead https://sernet.de/en/team-samba
>
>
