Segmentation fault on XpmCreateImageFromData(3)

[Matthieu Herrb]

On Wed, Mar 24, 2021 at 08:12:34PM -0300, Phillip Bushee wrote:
> I'm am writing a window manager which uses XpmCreateImageFromData(3)
> to read a .xpm file containing the theme of the decoration of the
> windows.  The program segfaults when calling this function.  I use this
> function rather than XpmCreatePixmapFromData(3) in order for me to get
> a pixel color from the .xpm with XGetPixel(3).

Hi,

I've the impression that this is happening because xa->valuemask is
being used unitialized in libXpm in the way you're calling it.

This seems to fix the crash for me:

diff --git shod.c shod.c
index 5dcb450..26865d7 100644
--- shod.c
+++ shod.c
@@ -467,6 +467,7 @@ settheme(void)
 	unsigned int i, j;
 	int status;
 
+	memset(&xa, 0, sizeof(xa));
 	if (config.theme_path)  /* if the we have specified a file, read it instead */
 		status = XpmReadFileToImage(dpy, config.theme_path, &img, NULL, &xa);
 	else                    /* else use the default theme */

> 
> This is the code of the window manager:
> 	https://github.com/phillbush/shod/blob/master/shod.c
> 
> This is the .xpm I am reading:
> 	https://github.com/phillbush/shod/blob/master/theme.xpm
> 
> This is what I get running the program under gdb.
> 
> 	GNU gdb 6.3
> 	Copyright 2004 Free Software Foundation, Inc.
> 	GDB is free software, covered by the GNU General Public License, and you
> are
> 	welcome to change it and/or distribute copies of it under certain
> conditions.
> 	Type "show copying" to see the conditions.
> 	There is absolutely no warranty for GDB.  Type "show warranty" for details.
> 	This GDB was configured as "amd64-unknown-openbsd6.8"...
> 	(gdb) run
> 	Starting program: /home/phil/proj/shod/shod
> 	Error while reading shared library symbols:
> 	Dwarf Error: wrong version in compilation unit header (is 4, should be 2)
> [in module /usr/libexec/ld.so]
> 	Error while reading shared library symbols:
> 	Dwarf Error: wrong version in compilation unit header (is 4, should be 2)
> [in module /usr/libexec/ld.so]
> 	Error while reading shared library symbols:
> 	Dwarf Error: wrong version in compilation unit header (is 4, should be 2)
> [in module /usr/libexec/ld.so]
> 	Error while reading shared library symbols:
> 	Dwarf Error: wrong version in compilation unit header (is 4, should be 2)
> [in module /usr/libexec/ld.so]
> 	Error while reading shared library symbols:
> 	Dwarf Error: wrong version in compilation unit header (is 4, should be 2)
> [in module /usr/libexec/ld.so]
> 
> 	Program received signal SIGSEGV, Segmentation fault.
> 	0x00007f7fffff2600 in ?? ()
> 	(gdb) bt
> 	#0  0x00007f7fffff2600 in ?? ()
> 	#1  0x00000960a406b734 in SetColor () from /usr/X11R6/lib/libXpm.so.9.0
> 	#2  0x00000960a4067ce6 in CreateColors () from /usr/X11R6/lib/libXpm.so.9.0
> 	#3  0x00000960a4069916 in xpmParseDataAndCreate () from
> /usr/X11R6/lib/libXpm.so.9.0
> 	#4  0x00000960a4065437 in XpmCreateImageFromData () from
> /usr/X11R6/lib/libXpm.so.9.0
> 	#5  0x0000095e5e85f5db in settheme () at shod.c:473
> 	#6  0x0000095e5e85bb58 in main () at shod.c:3465
> 
> I'm running OpenBSD Xenocara.
> This is what I get running `X -version`:
> 
> 	X.Org X Server 1.20.8
> 	X Protocol Version 11, Revision 0
> 	Build Operating System: OpenBSD 6.8 amd64
> 	Current Operating System: OpenBSD thinkbsd.my.domain 6.8 GENERIC.MP#5 amd64
> 	Build Date: 24 November 2020  06:57:35AM
> 
> 	Current version of pixman: 0.38.4
> 	        Before reporting problems, check http://wiki.x.org
> 	        to make sure that you have the latest version.
> 
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-- 
Matthieu Herrb