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#2 BUGFIX:Missing if(pframe) crashing kerne

closed-fixed
nobody
None
5
2002-11-29
2002-11-07
No

I had problems with my Logitech Quckcam Express P/N:
861050-0040, USB:46d/870/100,HDCS1000/id08 sensor.

Whenever I loaded mod_quickcam (version 0.40c) with
parameter
debug=32, it crashed the whole computer with CapsLock
and Scroll Lock diods blinking, keyboard and mouse
non-responding, Xserver stopped updating screen and
network layer seemed to be completely dead as well (no
ping returned). The same problem was reproduced
(including blinking two diods) on two completely
different computers with different versions of kernel
(SuSE)2.4.10 and (RedHat)2.4.18-17.7.x, but the same
version
of mod_quickcam 0.40c compiled from sources, and with
the same camera. Also has the same effect with SuSE
built-in qce driver
which is just bit older version.

I found the problem, and removed it and I am sending
the patch.

Explanation of the problem:
There is an inconsistency in one of "if
(debug&DEBUGINT) printk(...)". printk was referencing
pframe->storelength, without checking whether pframe
exists. It was checking if(pframe) just after this
printk. I found the same potential error somewhere
else. There was printk(...,pframe->...) and if(pframe)
AFTER it, which is nonsense. Either if(pframe) is
obsolete, or you need if(pframe) for printk as well.
The second mistake did not appear to cause problems
with my camera any of these computers, but I am sending
the fix of the second mistake as well, as the error
might crash computer under different circumstances.

After making patch the, driver works almost fluelessly
in RedHatLinux7.3 with xawtv and it cease to crash SuSE
Linux with debug=32 option. However xawtv still shows
green screen only under SuSE as before with debug=0.

Discussion

  • Ludvik Tesar

    Ludvik Tesar - 2002-11-07

    PATCH removing serious BUG, which crashes my computer with my camera.

     
  • Tuukka Toivonen

    Tuukka Toivonen - 2002-11-29
    • status: open --> closed-fixed
     

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