Bug 10846 - wrong XF86VidModeGetMonitor description
Summary: wrong XF86VidModeGetMonitor description
Alias: None
Product: xorg
Classification: Unclassified
Component: * Other (show other bugs)
Version: 7.2 (2007.02)
Hardware: Other All
: medium normal
Assignee: Xorg Project Team
QA Contact: Xorg Project Team
Depends on:
Blocks: xorg-7.4
  Show dependency treegraph
Reported: 2007-05-03 07:58 UTC by Werner Meisner
Modified: 2008-03-24 12:13 UTC (History)
0 users

See Also:
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i915 features:


Description Werner Meisner 2007-05-03 07:58:40 UTC
from  the man-page of XF86VidModeGetMonitor:

       Information  known  to the server about the monitor is returned by the XF
       function.  The hsync and vsync fields each point to an array of XF86VidMo
       tures.   The arrays contain nhsync and nvsync elements, respectively.  Th
       will be equal if a discreate value was given in the XF86Config file.

       The vendor, model, hsync, and vsync fields  point  to  dynamically  alloc
       should be freed by the caller.

dynamically allocated ??
not really

from XF86VMode.c

    if (rep.vendorLength)
        _XReadPad(dpy, monitor->vendor, rep.vendorLength);
        monitor->vendor = "";
    if (rep.modelLength)
        _XReadPad(dpy, monitor->model, rep.modelLength);
        monitor->model = "";
a pointer to a static "" is not dynamically!!

    XF86VidModeGetMonitor(dpy, DefaultScreen(dpy), &monitor)

    XFree(monitor.vendor);   -> crash
    XFree(monitor.model);    -> crash

were does the problem arise: xdpyinfo

   XFree86-VidModeExtension version 2.2 opcode: 134, base error: 130
     Monitor Information:
       Vendor: , Model: 
       Num hsync: 1, Num vsync: 1
       hsync range 0:  30.00 -  70.00
       vsync range 0:  47.00 -  85.00
   *** glibc detected *** ./xdpyinfo: munmap_chunk(): invalid pointer: 0xb7ec794
Comment 1 Adam Jackson 2008-03-24 12:13:54 UTC
Fixed in git, thanks!

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