Re: 2.6.7 fbcon: set_con2fb on current console = crash

On Saturday 19 June 2004 17:28, Geert Uytterhoeven wrote:

On Sat, 19 Jun 2004, Antonino A. Daplas wrote:

quoted

Thanks.  Actually there's still a critical flaw in the set_con2fbmap
code. For one, con2fb_map is never initialized.  It's just fortunate that
this array happens to be  filled with zeroes so con2fb_map[n] will always
return zero and registered_fb[0] happens to contain a valid info.  So it
works, by accident.

According to the C standard, global variables are initialized to zero,
unless specified otherwise.

I know, but what I meant was con2fb_map[] is never initialized by fbcon.  So 
if the first valid fbdev is in registered_fb[1], then con2fbmap must be 
initialized to 1's by fbcon.  It doesn't.  Note, fbdev-2.4 does the 
initialization correctly.

So 2 critical flaws in the code:

1. con2fb_map[] is always zero-set
2. fbcon assumes that registered_fb[0] is always valid

Both flaws will manifest by doing this:

modprobe fbdev1 - in registered_fb[0]
modprobe fbdev2 - in registered_fb[1]
rmmod fbdev1      - registered_fb[0] becomes invalid
modprobe fbcon  
	 - con2fb_map[] with zeroes instead of 1's and fbcon_startup looks for 
fb_info in registered_fb[0] instead of registered_fb[1]

Tony




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