On Thu, Oct 12, 2017 at 4:33 AM, Pavel Shilovsky <piastryyy@xxxxxxxxx> wrote:
> 2017-10-10 22:41 GMT-07:00 Ronnie Sahlberg <lsahlber@xxxxxxxxxx>:
>> This patch fixes the remaining issues with rsp_iov where
>> we might dereference uninitialized pointers or pass them
>> to free_rsp_buf().
>> There is also one memory leak that is fixed.
>>
>> Signed-off-by: Ronnie Sahlberg <lsahlber@xxxxxxxxxx>
>> ---
>> fs/cifs/smb2pdu.c | 43 +++++++++++++++++++++++++------------------
>> 1 file changed, 25 insertions(+), 18 deletions(-)
>>
>> diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
>> index 6ff4c275ca9a..fd2b2b8e86b0 100644
>> --- a/fs/cifs/smb2pdu.c
>> +++ b/fs/cifs/smb2pdu.c
>> @@ -470,7 +470,7 @@ SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses)
>> struct smb2_negotiate_req *req;
>> struct smb2_negotiate_rsp *rsp;
>> struct kvec iov[1];
>> - struct kvec rsp_iov;
>> + struct kvec rsp_iov = { NULL, 0 };
>> int rc = 0;
>> int resp_buftype;
>> struct TCP_Server_Info *server = ses->server;
>> @@ -1884,7 +1884,7 @@ SMB2_ioctl(const unsigned int xid, struct cifs_tcon *tcon, u64 persistent_fid,
>> struct smb2_sync_hdr *shdr;
>> struct cifs_ses *ses;
>> struct kvec iov[2];
>> - struct kvec rsp_iov;
>> + struct kvec rsp_iov = { NULL, 0 };
>> int resp_buftype;
>> int n_iov;
>> int rc = 0;
>> @@ -1981,6 +1981,8 @@ SMB2_ioctl(const unsigned int xid, struct cifs_tcon *tcon, u64 persistent_fid,
>> rc = SendReceive2(xid, ses, iov, n_iov, &resp_buftype, flags, &rsp_iov);
>> cifs_small_buf_release(req);
>> rsp = (struct smb2_ioctl_rsp *)rsp_iov.iov_base;
>> + if (rsp == NULL)
>> + goto ioctl_exit;
>
> Why do we need this? rsp pointer will be NULL if rc != 0 which is
> covered by the code below. Note that resp_buftype will be set to
> NO_BUFFER, so NULL/garbage pointer de-referencing shouldn't happen.
Thanks. I missed resp_buftype.
>
>>
>> if ((rc != 0) && (rc != -EINVAL)) {
>> cifs_stats_fail_inc(tcon, SMB2_IOCTL_HE);
>> @@ -2064,7 +2066,7 @@ SMB2_close(const unsigned int xid, struct cifs_tcon *tcon,
>> struct smb2_close_rsp *rsp;
>> struct cifs_ses *ses = tcon->ses;
>> struct kvec iov[1];
>> - struct kvec rsp_iov;
>> + struct kvec rsp_iov = { NULL, 0 };
>> int resp_buftype;
>> int rc = 0;
>> int flags = 0;
>> @@ -2168,9 +2170,9 @@ query_info(const unsigned int xid, struct cifs_tcon *tcon,
>> u32 *dlen)
>> {
>> struct smb2_query_info_req *req;
>> - struct smb2_query_info_rsp *rsp = NULL;
>> + struct smb2_query_info_rsp *rsp;
>> struct kvec iov[2];
>> - struct kvec rsp_iov;
>> + struct kvec rsp_iov = { NULL, 0 };
>> int rc = 0;
>> int resp_buftype;
>> struct cifs_ses *ses = tcon->ses;
>> @@ -2404,7 +2406,7 @@ SMB2_flush(const unsigned int xid, struct cifs_tcon *tcon, u64 persistent_fid,
>> struct smb2_flush_req *req;
>> struct cifs_ses *ses = tcon->ses;
>> struct kvec iov[1];
>> - struct kvec rsp_iov;
>> + struct kvec rsp_iov = { NULL, 0 };
>> int resp_buftype;
>> int rc = 0;
>> int flags = 0;
>> @@ -2639,10 +2641,10 @@ SMB2_read(const unsigned int xid, struct cifs_io_parms *io_parms,
>> {
>> int resp_buftype, rc = -EACCES;
>> struct smb2_read_plain_req *req = NULL;
>> - struct smb2_read_rsp *rsp = NULL;
>> + struct smb2_read_rsp *rsp;
>> struct smb2_sync_hdr *shdr;
>> struct kvec iov[2];
>> - struct kvec rsp_iov;
>> + struct kvec rsp_iov = { NULL, 0 };
>> unsigned int total_len;
>> __be32 req_len;
>> struct smb_rqst rqst = { .rq_iov = iov,
>> @@ -2669,6 +2671,10 @@ SMB2_read(const unsigned int xid, struct cifs_io_parms *io_parms,
>> cifs_small_buf_release(req);
>>
>> rsp = (struct smb2_read_rsp *)rsp_iov.iov_base;
>> + if (rsp == NULL) {
>> + cifs_dbg(VFS, "rsp is NULL in read\n");
>> + return -EIO;
>> + }
>> shdr = get_sync_hdr(rsp);
>
> This is another long-term bug, thanks. We should probably refactor the
> code a little bit here and move rc != 0 check before calling
> get_sync_hdr().
I will do that.
>
>>
>> if (shdr->Status == STATUS_END_OF_FILE) {
>> @@ -2856,9 +2862,9 @@ SMB2_write(const unsigned int xid, struct cifs_io_parms *io_parms,
>> {
>> int rc = 0;
>> struct smb2_write_req *req = NULL;
>> - struct smb2_write_rsp *rsp = NULL;
>> + struct smb2_write_rsp *rsp;
>> int resp_buftype;
>> - struct kvec rsp_iov;
>> + struct kvec rsp_iov = { NULL, 0 };
>> int flags = 0;
>>
>> *nbytes = 0;
>> @@ -2963,7 +2969,7 @@ SMB2_query_directory(const unsigned int xid, struct cifs_tcon *tcon,
>> struct smb2_query_directory_req *req;
>> struct smb2_query_directory_rsp *rsp = NULL;
>> struct kvec iov[2];
>> - struct kvec rsp_iov;
>> + struct kvec rsp_iov = { NULL, 0 };
>> int rc = 0;
>> int len;
>> int resp_buftype = CIFS_NO_BUFFER;
>> @@ -3093,9 +3099,9 @@ send_set_info(const unsigned int xid, struct cifs_tcon *tcon,
>> void **data, unsigned int *size)
>> {
>> struct smb2_set_info_req *req;
>> - struct smb2_set_info_rsp *rsp = NULL;
>> + struct smb2_set_info_rsp *rsp;
>> struct kvec *iov;
>> - struct kvec rsp_iov;
>> + struct kvec rsp_iov = { NULL, 0 };
>> int rc = 0;
>> int resp_buftype;
>> unsigned int i;
>> @@ -3376,9 +3382,9 @@ int
>> SMB2_QFS_info(const unsigned int xid, struct cifs_tcon *tcon,
>> u64 persistent_fid, u64 volatile_fid, struct kstatfs *fsdata)
>> {
>> - struct smb2_query_info_rsp *rsp = NULL;
>> + struct smb2_query_info_rsp *rsp;
>> struct kvec iov;
>> - struct kvec rsp_iov;
>> + struct kvec rsp_iov = { NULL, 0 };
>> int rc = 0;
>> int resp_buftype;
>> struct cifs_ses *ses = tcon->ses;
>> @@ -3419,9 +3425,9 @@ int
>> SMB2_QFS_attr(const unsigned int xid, struct cifs_tcon *tcon,
>> u64 persistent_fid, u64 volatile_fid, int level)
>> {
>> - struct smb2_query_info_rsp *rsp = NULL;
>> + struct smb2_query_info_rsp *rsp;
>> struct kvec iov;
>> - struct kvec rsp_iov;
>> + struct kvec rsp_iov = { NULL, 0 };
>> int rc = 0;
>> int resp_buftype, max_len, min_len;
>> struct cifs_ses *ses = tcon->ses;
>> @@ -3492,7 +3498,7 @@ smb2_lockv(const unsigned int xid, struct cifs_tcon *tcon,
>> int rc = 0;
>> struct smb2_lock_req *req = NULL;
>> struct kvec iov[2];
>> - struct kvec rsp_iov;
>> + struct kvec rsp_iov = { NULL, 0 };
>> int resp_buf_type;
>> unsigned int count;
>> int flags = CIFS_NO_RESP;
>> @@ -3525,6 +3531,7 @@ smb2_lockv(const unsigned int xid, struct cifs_tcon *tcon,
>> rc = SendReceive2(xid, tcon->ses, iov, 2, &resp_buf_type, flags,
>> &rsp_iov);
>> cifs_small_buf_release(req);
>> + free_rsp_buf(resp_buf_type, rsp_iov.iov_base);
>
> flags == CIFS_NO_RESP above, so, no memory leak should happen and do
> not need to call free_rsp_buf().
I see. thanks.
>
>> if (rc) {
>> cifs_dbg(FYI, "Send error in smb2_lockv = %d\n", rc);
>> cifs_stats_fail_inc(tcon, SMB2_LOCK_HE);
>> --
>> 2.13.3
>>
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>
> That's being said I think we need to merge "[PATCH 06/12] cifs:
> initialize rsp_iov in SMB2_read and add check for NULL" with a stable
> tag because it fixes the real bug.
>
> I am not apposite of initializing struct kvec rsp_iov to { NULL, 0 }
> but it doesn't seem suitable to stable kernels because like in
> SMB2_ioctl() example we do not cause problems calling
> free_rsp_buf(resp_buftype, rsp) with resp_buftype == CIFS_NO_BUFFER.
>
> --
> Best regards,
> Pavel Shilovsky
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