1 files changed, 9 insertions, 4 deletions

diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c
index c2ac36dfe4f3..18de84c8ccd8 100644
--- a/block/scsi_ioctl.c
+++ b/block/scsi_ioctl.c
@@ -190,16 +190,21 @@ static int verify_command(struct file *file, unsigned char *cmd)
                 safe_for_write(GPCMD_SET_STREAMING),
         };
         unsigned char type = cmd_type[cmd[0]];
+        int has_write_perm = 0;
 
         /* Anybody who can open the device can do a read-safe command */
         if (type & CMD_READ_SAFE)
                 return 0;
 
+        /*
+         * file can be NULL from ioctl_by_bdev()...
+         */
+        if (file)
+                has_write_perm = file->f_mode & FMODE_WRITE;
+
         /* Write-safe commands just require a writable open.. */
-        if (type & CMD_WRITE_SAFE) {
-                if (file->f_mode & FMODE_WRITE)
-                        return 0;
-        }
+        if ((type & CMD_WRITE_SAFE) && has_write_perm)
+                return 0;
 
         /* And root can do any command.. */
         if (capable(CAP_SYS_RAWIO))