After updating to server 1.7.3 the X server started segfaulting with some ATI drivers.

According to the reports sent to me, 1.7.2 was working fine, and only at the update from 1.7.2 to 1.7.3 the problem started happening.

Here is the backtrace:
#0  RADEONGetDrawablePixmap (pDrawable=0x0) at radeon_exa_render.c:464
#1  0xb7159eb2 in R600CheckComposite (op=3, pSrcPicture=0x9c08d18, 
    pMaskPicture=0x9c09568, pDstPicture=0x9c089e0) at r600_exa.c:1316
#2  0xb6f37d26 in exaTryDriverComposite (op=0 '\0', pSrc=<value optimized out>, 
    pMask=0x9c09568, pDst=0x9c089e0, xSrc=12, ySrc=32, xMask=0, yMask=0, xDst=12, 
    yDst=32, width=62, height=30) at exa_render.c:695
#3  0xb6f38dab in exaComposite (op=3 '\003', pSrc=0x9c08d18, pMask=0x9c09568, 
    pDst=0x9c089e0, xSrc=12, ySrc=32, xMask=0, yMask=0, xDst=12, yDst=32, width=62, 
    height=30) at exa_render.c:1034
#4  0x08122dda in damageComposite (op=96 '`', pSrc=0x9c08d18, pMask=0x9c09568, 
    pDst=0x9c089e0, xSrc=<value optimized out>, ySrc=<value optimized out>, 
    xMask=<value optimized out>, yMask=<value optimized out>, 
    xDst=<value optimized out>, yDst=<value optimized out>, 
    width=<value optimized out>, height=<value optimized out>) at damage.c:643
#5  0x0811618e in CompositePicture (op=3 '\003', pSrc=0x9c08d18, pMask=0x9c09568, 
    pDst=0x9c089e0, xSrc=12, ySrc=32, xMask=<value optimized out>, 
    yMask=<value optimized out>, xDst=<value optimized out>, 
    yDst=<value optimized out>, width=62, height=30) at picture.c:1718
#6  0xb6f37a05 in exaTrapezoids (op=0 '\0', pSrc=0x9c08d18, pDst=0x9c089e0, 
    maskFormat=0x999b198, xSrc=15, ySrc=32, ntrap=0, traps=0x9be1fd8)
    at exa_render.c:1183
#7  0x08115e0a in CompositeTrapezoids (op=96 '`', pSrc=0x9c08d18, pDst=0x9c089e0, 
    maskFormat=0x999b198, xSrc=15, ySrc=<value optimized out>, ntrap=9, 
    traps=0x9be1e70) at picture.c:1759
#8  0x0811ecc8 in ProcRenderTrapezoids (client=0x9bddba0) at render.c:780
#9  0x08118e81 in ProcRenderDispatch (client=0xb7159e60) at render.c:2056
#10 0x0806ea87 in Dispatch () at dispatch.c:445
#11 0x08063055 in main (argc=2, argv=0xbfedfd04, envp=0xbfedfd10) at main.c:286



How to reproduce:
It's very easy to reproduce... Just start using gnome and you'll eventually see the crash.

How I was reproducing the bug in my tests:
- X -retro &
- DISPLAY=:0.0 gnome-appearance-properties

With this I could reproduce the bug 100% of the times.


What I tried:
- using radeon 6.12.4 the crash happens
- so I tried to recompile the driver... the crash still happens
- using the radeon driver from git (7 december 2009) the problem *doesn't* happen
- using the radeon git branch "6.12-branch" (which is a little bit newer than 6.12.4) the crash still happens