Note: This is a beta release of Red Hat Bugzilla 5.0. The data contained within is a snapshot of the live data so any changes you make will not be reflected in the production Bugzilla. Also email is disabled so feel free to test any aspect of the site that you want. File any problems you find or give feedback here.

Bug 18

Summary: mt may pass incorrect values in its ioctl() calls
Product: [Retired] Red Hat Linux Reporter: mikpe
Component: mt-stAssignee: Preston Brown <pbrown>
Severity: medium Docs Contact:
Priority: medium    
Version: 5.2   
Target Milestone: ---   
Target Release: ---   
Hardware: All   
OS: Linux   
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 1999-02-10 21:32:55 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:

Description mikpe 1998-11-10 06:26:41 UTC
RH 5.2's "mt" command is built from mt-st-0.5, which
contains a rather annoying bug.

The bug occurs when (a) the -f <device> option is used,
and (b) a command is given which requires a "count" or
some subcommands, eg. "mt -f /dev/nftape drvbuffer 16".

The bug is that in these cases, the count/subcommands are
read from the wrong elements of main()'s argv[], as if
the -f option wasn't given, leading to incorrect values
being passed in ioctl calls to the tape's device driver.

A temporary workaround is to avoid the -f option, and
instead set TAPE=<your tape device> in the environment.

The proper fix is to apply the following trivial patch:

--- mt-st-0.5/mt.c.~1~  Sat Apr 11 16:58:25 1998
+++ mt-st-0.5/mt.c      Tue Nov 10 11:02:11 1998
@@ -282,7 +282,7 @@
        mtfd = (-1);

     if (comp->cmd_function != NULL)
-       i = comp->cmd_function(mtfd, comp, argc - 2,
+       i = comp->cmd_function(mtfd, comp, argc - argn,
     else {
        fprintf(stderr, "mt: Internal error: command without
        i = 1;


Comment 1 hargrove 1998-11-25 21:13:59 UTC
This bug is fixed in mt-st-0.5b available from

Comment 2 Preston Brown 1999-02-10 21:32:59 UTC
this has been fixed in rawhide.

Comment 3 jhart 2000-02-18 13:11:59 UTC
This bug appears to persist in 0.5b.  I still get it on setdensity
with an exb-8200

mt -f /dev/nst0 setdensity 20

Comment 4 jhart 2000-02-19 00:33:59 UTC
further investigation indicates the arguments are passed correctly by mt-st
0.5b, but the ioctl() is rejected by the driver or the exb-8200, so it is not
the same bug after all