Overview:

This bug was first reported at the KDE bug tracker (https://bugs.kde.org/show_bug.cgi?id=227922), but it seems to be X-related. The version of KMail that triggered this was 1.12.4, although it has happened in past versions as well. The same bug has occured when using either the fglrx or the radeonhd driver (speculation: it's not driver related). The crash doesn't happen every time the composer is used (in fact, it seems to pick the worst possible times to occur).

Xorg.0.log.old contains the following backtrace:

0: /usr/bin/X (xorg_backtrace+0x3b) [0x80e696b]
1: /usr/bin/X (0x8048000+0x60b75) [0x80a8b75]
2: (vdso) (__kernel_rt_sigreturn+0x0) [0xb770e40c]
3: /usr/bin/X (FindGlyphByHash+0x3c) [0x81b346c]
4: /usr/bin/X (0x8048000+0xcfa22) [0x8117a22]
5: /usr/bin/X (0x8048000+0xca553) [0x8112553]
6: /usr/bin/X (0x8048000+0x2b017) [0x8073017]
7: /usr/bin/X (0x8048000+0x1e95a) [0x806695a]
8: /lib/i686/cmov/libc.so.6 (__libc_start_main+0xe5) [0xb7423b55]
9: /usr/bin/X (0x8048000+0x1e541) [0x8066541]
Segmentation fault at address 0x4

Having installed the core X server debugging symbols (debian package xserver-xorg-core-dbg), I ran addr2line on the addresses of the above backtrace versus /usr/lib/debug/usr/bin/Xorg and got the following:

0: xorg_backtrace
/home/bgoglin/debian/git/xserver/xorg-server-1.7.5/build/os/../../os/backtrace.c:46
1: OsSigHandler
/home/bgoglin/debian/git/xserver/xorg-server-1.7.5/build/os/../../os/osinit.c:142
3: FindGlyphByHash
/home/bgoglin/debian/git/xserver/xorg-server-1.7.5/build/render/../../render/glyph.c:263
4: ProcRenderAddGlyphs
/home/bgoglin/debian/git/xserver/xorg-server-1.7.5/build/render/../../render/render.c:1107
5: ProcRenderDispatch
/home/bgoglin/debian/git/xserver/xorg-server-1.7.5/build/render/../../render/render.c:2059
6: Dispatch
/home/bgoglin/debian/git/xserver/xorg-server-1.7.5/build/dix/../../dix/dispatch.c:440
7: main
/home/bgoglin/debian/git/xserver/xorg-server-1.7.5/build/dix/../../dix/main.c:287

Please note that the names of the debug binary and the running one don't match ("X" versus "Xorg", there was no "X" debug binary included in the package), so I'm not sure if the above output is valid. Check the bug entry on KDE's bug tracker for more backtraces by another user.

Since the crash happens inside FindGlyphByHash, it was suggested that my font cache is somehow corrupted. The only fiddling I have done with the font cache was when I refreshed it upon adding some new fonts to ~/.fonts.


Steps to Reproduce:

1)  Start KMail.
2a) Click the "New Message" toolbar button to start the email composer.
      or
2b) Click the "Reply" toolbar button with a message selected.


Actual Results:

The X server (sometimes) crashes, then restarts. Please note that the composer window never appears before the screen goes black.


Expected Results:

The composer window should appear. The X server shouldn't crash.


Build Date & Platform:

(X.org version 1.7.5) Build 2010-02-16 on Linux 2.6.32-trunk-686 i686 Debian (current version on Debian Testing)


Additional Builds and Platforms:

Kubuntu 9.10 build, X.org version 1.6.4 (as reported on the KDE bug tracker by Ralf Jung)