Fix for a crash under FVWM3

[bsdmp]

Core was generated by `rofi'.
Program terminated with signal SIGSEGV, Segmentation fault. 0 strlen () at /usr/src/lib/libc/arch/amd64/string/strlen.S:125
125 movq (%rax),%rdx /* get bytes to check */
(gdb) bt
0 strlen () at /usr/src/lib/libc/arch/amd64/string/strlen.S:125
1 0x000008dfab6e1558 in __vfprintf (fp=, fmt0=, ap=) at /usr/src/lib/libc/stdio/vfprintf.c:877
2 0x000008dfab6da5a5 in _libc_vasprintf (str=0x7de1bf300610, fmt=0x8dd3e926e47 "Found window manager: |%s|", ap=0x7de1bf300800) at /usr/src/lib/libc/stdio/vasprintf.c:43
3 0x000008df5bfdfac7 in g_vasprintf () from /usr/local/lib/libglib-2.0.so.4201.10
4 0x000008df5bfa412d in g_strdup_vprintf () from /usr/local/lib/libglib-2.0.so.4201.10
5 0x000008df5bf86b3b in g_logv () from /usr/local/lib/libglib-2.0.so.4201.10
6 0x000008df5bf86a55 in g_log () from /usr/local/lib/libglib-2.0.so.4201.10
7 0x000008dd3e9853b2 in x11_helper_discover_window_manager () at ../source/xcb.c:1639
8 0x000008dd3e984d18 in display_setup (main_loop=0x8df6826b320, bindings=0x8df77e08220) at ../source/xcb.c:1696
9 0x000008dd3e954c03 in main (argc=9, argv=0x7de1bf300a58) at ../source/rofi.c:1021
(gdb) f 7
7 0x000008dd3e9853b2 in x11_helper_discover_window_manager () at ../source/xcb.c:1639
1639 g_debug("Found window manager: |%s|", wtitle.strings);
(gdb) p wtitle.strings
$1 = 0x8dfb80a2f50 "FVWM", '\325' <repeats 12 times>, '\337' <repeats 159 times>, <incomplete sequence \337><error: Cannot access memory at address 0x8dfb80a3000>

wtitle.strings is not NULL terminated, handle it with providing string length

Patch by Omar Polo

https://marc.info/?l=openbsd-ports&m=169606431614242&w=2

[DaveDavenport]

Thanks, I think this might need a bit more of a fix to be sure as the non null terminated string is used later.. Ill look at it later.

[DaveDavenport]

Can you test:

diff --git a/source/xcb.c b/source/xcb.c
index 375cfcfc..4e103979 100644
--- a/source/xcb.c
+++ b/source/xcb.c
@@ -1617,7 +1617,7 @@ char *x11_helper_get_window_manager(void) {
         xcb_ewmh_get_wm_name_unchecked(&(xcb->ewmh), wm_win);
     if (xcb_ewmh_get_wm_name_reply(&(xcb->ewmh), cookie, &wtitle, (void *)0)) {
       if (wtitle.strings_len > 0) {
-        retv = g_strdup(wtitle.strings);
+        retv = g_strndup(wtitle.strings, wtitle.strings_len);
       }
       xcb_ewmh_get_utf8_strings_reply_wipe(&wtitle);
     }
@@ -1636,13 +1636,16 @@ static void x11_helper_discover_window_manager(void) {
         xcb_ewmh_get_wm_name_unchecked(&(xcb->ewmh), wm_win);
     if (xcb_ewmh_get_wm_name_reply(&(xcb->ewmh), cookie, &wtitle, (void *)0)) {
       if (wtitle.strings_len > 0) {
-        g_debug("Found window manager: |%s|", wtitle.strings);
-        if (g_strcmp0(wtitle.strings, "i3") == 0) {
+        // Copy the string and add terminating '\0'.
+        char *str = g_strndup(wtitle.strings, wtitle.strings_len);
+        g_debug("Found window manager: |%s|", str);
+        if (g_strcmp0(str, "i3") == 0) {
           current_window_manager =
               WM_DO_NOT_CHANGE_CURRENT_DESKTOP | WM_PANGO_WORKSPACE_NAMES;
-        } else if (g_strcmp0(wtitle.strings, "bspwm") == 0) {
+        } else if (g_strcmp0(str, "bspwm") == 0) {
           current_window_manager = WM_ROOT_WINDOW_OFFSET;
         }
+        g_free(str);
       }
       xcb_ewmh_get_utf8_strings_reply_wipe(&wtitle);
     }

[bsdmp]

100 iterations - no crash

[DaveDavenport]

Thanks for testing.

[DaveDavenport]

Added the fix to git.

[DaveDavenport]

Thanks

[github-actions]

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