Author: jhb
Date: Tue Apr 21 17:47:05 2020
New Revision: 360171
URL: https://svnweb.freebsd.org/changeset/base/360171

Log:
  Don't access a user buffer directly from the kernel.
  
  The handle_string callback for the ENCIOC_SETSTRING ioctl was passing
  a user pointer to memcpy().  Fix by using copyin() instead.
  
  For ENCIOC_GETSTRING ioctls, the handler was storing the user pointer
  in a CCB's data_ptr field where it was indirected by other code.  Fix
  this by allocating a temporary buffer (which ENCIOC_SETSTRING already
  did) and copying the result out to the user buffer after the CCB has
  been processed.
  
  Reviewed by:  kib
  Obtained from:        CheriBSD
  MFC after:    1 week
  Sponsored by: DARPA
  Differential Revision:        https://reviews.freebsd.org/D24487

Modified:
  head/sys/cam/scsi/scsi_enc_ses.c

Modified: head/sys/cam/scsi/scsi_enc_ses.c
==============================================================================
--- head/sys/cam/scsi/scsi_enc_ses.c    Tue Apr 21 17:42:32 2020        
(r360170)
+++ head/sys/cam/scsi/scsi_enc_ses.c    Tue Apr 21 17:47:05 2020        
(r360171)
@@ -2904,13 +2904,19 @@ ses_handle_string(enc_softc_t *enc, encioc_string_t *s
                buf[1] = 0;
                buf[2] = sstr->bufsiz >> 8;
                buf[3] = sstr->bufsiz & 0xff;
-               memcpy(&buf[4], sstr->buf, sstr->bufsiz);
+               ret = copyin(sstr->buf, &buf[4], sstr->bufsiz);
+               if (ret != 0) {
+                       ENC_FREE(buf);
+                       return (ret);
+               }
                break;
        case ENCIOC_GETSTRING:
                payload = sstr->bufsiz;
                amt = payload;
+               buf = ENC_MALLOC(payload);
+               if (buf == NULL)
+                       return (ENOMEM);
                ses_page_cdb(cdb, payload, SesStringIn, CAM_DIR_IN);
-               buf = sstr->buf;
                break;
        case ENCIOC_GETENCNAME:
                if (ses_cache->ses_nsubencs < 1)
@@ -2950,6 +2956,8 @@ ses_handle_string(enc_softc_t *enc, encioc_string_t *s
                return (EINVAL);
        }
        ret = enc_runcmd(enc, cdb, 6, buf, &amt);
+       if (ret == 0 && ioc == ENCIOC_GETSTRING)
+               ret = copyout(buf, sstr->buf, sstr->bufsiz);
        if (ioc == ENCIOC_SETSTRING)
                ENC_FREE(buf);
        return (ret);
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