> Subject: RE: [Patch v2 2/6] cifs: Allocate validate negotiation request through
> kmalloc
>
> > -----Original Message-----
> > From: linux-kernel-owner@xxxxxxxxxxxxxxx
> > <linux-kernel-owner@xxxxxxxxxxxxxxx> On Behalf Of Long Li
> > Sent: Tuesday, April 17, 2018 12:17 PM
> > To: Steve French <sfrench@xxxxxxxxx>; linux-cifs@xxxxxxxxxxxxxxx;
> > samba- technical@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> > linux-rdma@xxxxxxxxxxxxxxx
> > Cc: Long Li <longli@xxxxxxxxxxxxx>; stable@xxxxxxxxxxxxxxx
> > Subject: [Patch v2 2/6] cifs: Allocate validate negotiation request
> > through kmalloc
> >
> > From: Long Li <longli@xxxxxxxxxxxxx>
> >
> > The data buffer allocated on the stack can't be DMA'ed, and hence
> > can't send through RDMA via SMB Direct.
> >
> > Fix this by allocating the request on the heap in smb3_validate_negotiate.
> >
> > Fixes: ff1c038addc4f205d5f1ede449426c7d316c0eed "Check SMB3 dialects
> > against downgrade attacks"
> >
> > Changes in v2:
> > Removed duplicated code on freeing buffers on function exit.
> > (Thanks to Parav Pandit <parav@xxxxxxxxxxxx>)
> >
> > Fixed typo in the patch title.
> >
> > Signed-off-by: Long Li <longli@xxxxxxxxxxxxx>
> > Cc: stable@xxxxxxxxxxxxxxx
> > ---
> > fs/cifs/smb2pdu.c | 57
> > ++++++++++++++++++++++++++++++-------------------------
> > 1 file changed, 31 insertions(+), 26 deletions(-)
> >
> > diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c index
> > 0f044c4..41625e4 100644
> > --- a/fs/cifs/smb2pdu.c
> > +++ b/fs/cifs/smb2pdu.c
> > @@ -729,8 +729,8 @@ SMB2_negotiate(const unsigned int xid, struct
> > cifs_ses *ses)
> >
> > int smb3_validate_negotiate(const unsigned int xid, struct cifs_tcon
> > *tcon) {
> > - int rc = 0;
> > - struct validate_negotiate_info_req vneg_inbuf;
> > + int ret, rc = -EIO;
> > + struct validate_negotiate_info_req *pneg_inbuf;
> > struct validate_negotiate_info_rsp *pneg_rsp = NULL;
> > u32 rsplen;
> > u32 inbuflen; /* max of 4 dialects */ @@ -741,6 +741,9 @@ int
> > smb3_validate_negotiate(const unsigned int xid, struct cifs_tcon
> > *tcon)
> > if (tcon->ses->server->rdma)
> > return 0;
> > #endif
> > + pneg_inbuf = kmalloc(sizeof(*pneg_inbuf), GFP_KERNEL);
> > + if (!pneg_inbuf)
> > + return -ENOMEM;
>
> Immediately after the above new code, there are three if statements that
> can 'return 0' and never free the pneg_inbuf memory. They should instead
> set 'rc'
> appropriately and 'goto' the out_free_inbuf label.
Thanks!
I will move the kmalloc after those statements.
>
> Michael
>
> >
> > /* In SMB3.11 preauth integrity supersedes validate negotiate */
> > if (tcon->ses->server->dialect == SMB311_PROT_ID) @@ -764,53
> +767,53
> > @@ int smb3_validate_negotiate(const unsigned int xid, struct
> > cifs_tcon
> > *tcon)
> > if (tcon->ses->session_flags & SMB2_SESSION_FLAG_IS_NULL)
> > cifs_dbg(VFS, "Unexpected null user (anonymous) auth flag
> sent by
> > server\n");
> >
> > - vneg_inbuf.Capabilities =
> > + pneg_inbuf->Capabilities =
> > cpu_to_le32(tcon->ses->server->vals-
> >req_capabilities);
> > - memcpy(vneg_inbuf.Guid, tcon->ses->server->client_guid,
> > + memcpy(pneg_inbuf->Guid, tcon->ses->server->client_guid,
> > SMB2_CLIENT_GUID_SIZE);
> >
> > if (tcon->ses->sign)
> > - vneg_inbuf.SecurityMode =
> > + pneg_inbuf->SecurityMode =
> >
> cpu_to_le16(SMB2_NEGOTIATE_SIGNING_REQUIRED);
> > else if (global_secflags & CIFSSEC_MAY_SIGN)
> > - vneg_inbuf.SecurityMode =
> > + pneg_inbuf->SecurityMode =
> >
> cpu_to_le16(SMB2_NEGOTIATE_SIGNING_ENABLED);
> > else
> > - vneg_inbuf.SecurityMode = 0;
> > + pneg_inbuf->SecurityMode = 0;
> >
> >
> > if (strcmp(tcon->ses->server->vals->version_string,
> > SMB3ANY_VERSION_STRING) == 0) {
> > - vneg_inbuf.Dialects[0] = cpu_to_le16(SMB30_PROT_ID);
> > - vneg_inbuf.Dialects[1] = cpu_to_le16(SMB302_PROT_ID);
> > - vneg_inbuf.DialectCount = cpu_to_le16(2);
> > + pneg_inbuf->Dialects[0] = cpu_to_le16(SMB30_PROT_ID);
> > + pneg_inbuf->Dialects[1] = cpu_to_le16(SMB302_PROT_ID);
> > + pneg_inbuf->DialectCount = cpu_to_le16(2);
> > /* structure is big enough for 3 dialects, sending only 2 */
> > inbuflen = sizeof(struct validate_negotiate_info_req) - 2;
> > } else if (strcmp(tcon->ses->server->vals->version_string,
> > SMBDEFAULT_VERSION_STRING) == 0) {
> > - vneg_inbuf.Dialects[0] = cpu_to_le16(SMB21_PROT_ID);
> > - vneg_inbuf.Dialects[1] = cpu_to_le16(SMB30_PROT_ID);
> > - vneg_inbuf.Dialects[2] = cpu_to_le16(SMB302_PROT_ID);
> > - vneg_inbuf.DialectCount = cpu_to_le16(3);
> > + pneg_inbuf->Dialects[0] = cpu_to_le16(SMB21_PROT_ID);
> > + pneg_inbuf->Dialects[1] = cpu_to_le16(SMB30_PROT_ID);
> > + pneg_inbuf->Dialects[2] = cpu_to_le16(SMB302_PROT_ID);
> > + pneg_inbuf->DialectCount = cpu_to_le16(3);
> > /* structure is big enough for 3 dialects */
> > inbuflen = sizeof(struct validate_negotiate_info_req);
> > } else {
> > /* otherwise specific dialect was requested */
> > - vneg_inbuf.Dialects[0] =
> > + pneg_inbuf->Dialects[0] =
> > cpu_to_le16(tcon->ses->server->vals->protocol_id);
> > - vneg_inbuf.DialectCount = cpu_to_le16(1);
> > + pneg_inbuf->DialectCount = cpu_to_le16(1);
> > /* structure is big enough for 3 dialects, sending only 1 */
> > inbuflen = sizeof(struct validate_negotiate_info_req) - 4;
> > }
> >
> > - rc = SMB2_ioctl(xid, tcon, NO_FILE_ID, NO_FILE_ID,
> > + ret = SMB2_ioctl(xid, tcon, NO_FILE_ID, NO_FILE_ID,
> > FSCTL_VALIDATE_NEGOTIATE_INFO, true /* is_fsctl */,
> > - (char *)&vneg_inbuf, sizeof(struct
> validate_negotiate_info_req),
> > + (char *)pneg_inbuf, sizeof(struct
> validate_negotiate_info_req),
> > (char **)&pneg_rsp, &rsplen);
> >
> > - if (rc != 0) {
> > - cifs_dbg(VFS, "validate protocol negotiate failed: %d\n", rc);
> > - return -EIO;
> > + if (ret != 0) {
> > + cifs_dbg(VFS, "validate protocol negotiate failed: %d\n", ret);
> > + goto out_free_inbuf;
> > }
> >
> > if (rsplen != sizeof(struct validate_negotiate_info_rsp)) { @@
> > -820,7 +823,7 @@ int smb3_validate_negotiate(const unsigned int xid,
> > struct cifs_tcon
> > *tcon)
> > /* relax check since Mac returns max bufsize allowed on ioctl
> */
> > if ((rsplen > CIFSMaxBufSize)
> > || (rsplen < sizeof(struct validate_negotiate_info_rsp)))
> > - goto err_rsp_free;
> > + goto out_free_rsp;
> > }
> >
> > /* check validate negotiate info response matches what we got
> > earlier */ @@ -838,14 +841,16 @@ int smb3_validate_negotiate(const
> > unsigned int xid, struct cifs_tcon
> > *tcon)
> >
> > /* validate negotiate successful */
> > cifs_dbg(FYI, "validate negotiate info successful\n");
> > - kfree(pneg_rsp);
> > - return 0;
> > + rc = 0;
> > + goto out_free_rsp;
> >
> > vneg_out:
> > cifs_dbg(VFS, "protocol revalidation - security settings
> > mismatch\n");
> > -err_rsp_free:
> > +out_free_rsp:
> > kfree(pneg_rsp);
> > - return -EIO;
> > +out_free_inbuf:
> > + kfree(pneg_inbuf);
> > + return rc;
> > }
> >
> > enum securityEnum
> > --
> > 2.7.4