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.
>
> 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().
>
> 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().
> 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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