[BusyBox] SegFault into 'make menuconfig'

[Glenn McGrath]

On Fri, 13 Dec 2002 16:46:09 +0200 (EET)
Nick Fedchik <fnm at fusion.ukrsat.com> wrote:

> Hi ALL!
> 
> make menuconfig on busybox 0.61pre (daily from cvs).
> Interest situation - when I entering File Utilities section,
> just moving cursor down to the end to
> [*]   Support for human readable output (example 13k, 23M, 235G)
> then moving cursor up to
> [*] rm
> and again up to [*] mv
> 

Yea, i get that segfaults as well, i thought it was something specific to
me, ive been wondering about it for a while, taking another look now i see
a pattern.


See if you can duplicate this.

1)
In the main menu scroll down (with down arrow, not pagedown) to the 4th
line from the bottom, "Debugging Options" (no further), and then press up
arrow 8 times untill you are at "Module Utilities".

The top line say "---" (3rd line from the bottom), which is not what
it should be.

If you scroll up once the top line changes to "Linux System Utilities",
which is the 5th line from the bottom (and again incorrect).

The pattern continues as you keep scrolling up.

2)
In the main menu scroll down (with down arrow, not pagedown) to the 3rd
line from the bottom, "---" seperator (no further), and then press up
arrow 8 times until you are at "Network Utilities".

The top line say "Save Configuration to an Alternate File" (very bottom
line), which again is incorrect.

If you scroll up once, the top line will change to "---", which is the 3rd
line from the bottom, and again incorrect.

The pattern continues as you keep scrolling up.

2a) this behavious starts with "Miscellaneous Utilities", which is lines
below a full screen of options, 8 is the number of items that can be moved
through without needing to scroll.

3)
In the main menu scroll down (with down arrow, not pagedown) to the 2nd
line from the bottom, "Load an Alternate Configuration File" (no further),
and then press up arrow 8 times until you are at "Another Bourne-like
Shell".

The behaviour is different here as the top line is correct, to be
consistent with the above bug the top line would 2 lines below the last
line (which it cant do obviously, it would probably be a bad pointer).

But when you scroll up one line it segfaults, maybe its incrementing the
bad pointer by 2 ?


The behaviour happens in the Files menu as well, and i susspect any menu
that needs to be scrolled.

I wonder if it happens in other projects that use kbuild ?

I dont see how this could be anything but a bug in kbuild, but then why
isnt everyone else seeing it ?


Glenn