Bug#422483: gdm: segfault after XDMCP chooser

[Sylvain Le Gall]

On Sun, May 06, 2007 at 03:27:15PM +0200, Loïc Minier wrote:
> On Sun, May 06, 2007, Sylvain Le Gall wrote:
> > Well, i set severity to important because, it render the package useless
> > for me (but it only affects XDMCP related configuration, which is not
> > the most common way to use gdm).
> > 
> > My bug is as follow:
> > * i have a XEN configuration (dom0 = debian etch, X + vesa xserver)
> > * i use GDM in domU yocto (debian unstable, no X)
> > * in dom0: X -indirect yocto 
> > * in domU: i attach gdm.conf 
> > * i can see and choose yocto in the chooser screen of gdm (of yocto)
> > * once i try to connect to login screen of yocto, GDM segfault
> > * i have downgraded to 2.16.4 and it works again
> > 
> > I have a message in /var/log/gdm/:0.log
> > /etc/X11/X is not executable
> 
>  I don't know whether the message is to be taken seriously or not,
>  however could you please try attaching a gdb to your gdm after it's
>  started and before it crashes, then type "continue", then crash it,
>  then report the backtrace?
> 
>    Thanks!
> 
Here is the backtrace.

(gdb) continue
Continuing.

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 47349274408464 (LWP 6652)]
0x0000000000424ec1 in ?? ()
(gdb) backtrace
#0  0x0000000000424ec1 in ?? ()
#1  0x0000000000429f9c in ?? ()
#2  0x000000000042c066 in ?? ()
#3  0x00002b105baa5d93 in g_main_context_dispatch ()
   from /usr/lib/libglib-2.0.so.0
#4  0x00002b105baa8bdd in ?? () from /usr/lib/libglib-2.0.so.0
#5  0x00002b105baa8ec6 in g_main_loop_run () from
/usr/lib/libglib-2.0.so.0
#6  0x000000000040a52c in ?? ()
#7  0x00002b105bc348e4 in __libc_start_main () from /lib/libc.so.6
#8  0x0000000000408a79 in ?? ()
#9  0x00007fff51c3b968 in ?? ()
#10 0x0000000000000000 in ?? ()
(gdb)

I see no function name, i think that i have a debug stripped binary.
Maybe, this is not as useful as you want.

Another information (strace gdm --nodaemon): 
rt_sigaction(SIGTERM, {0x424110, [], SA_RESTORER|SA_RESTART,
0x2b20f9e49ca0}, {0x435870, [], SA_RESTORER|SA_RESTART, 0x2b20f9e49ca0},
8) = 0
rt_sigaction(SIGINT, {0x424110, [], SA_RESTORER|SA_RESTART,
0x2b20f9e49ca0}, {0x435870, [], SA_RESTORER|SA_RESTART, 0x2b20f9e49ca0},
8) = 0
rt_sigaction(SIGHUP, {0x424110, [], SA_RESTORER|SA_RESTART,
0x2b20f9e49ca0}, {0x435870, [], SA_RESTORER|SA_RESTART, 0x2b20f9e49ca0},
8) = 0
rt_sigprocmask(SIG_BLOCK, NULL, [], 8)  = 0
socket(PF_NETLINK, SOCK_RAW, 0)         = 8
bind(8, {sa_family=AF_NETLINK, pid=0, groups=00000000}, 12) = 0
getsockname(8, {sa_family=AF_NETLINK, pid=6689, groups=00000000},
[206158430220]) = 0
time(NULL)                              = 1178471968
sendto(8, "\24\0\0\0\26\0\1\3 \16>F\0\0\0\0\0\0\0\0", 20, 0,
{sa_family=AF_NETLINK, pid=0, groups=00000000}, 12) = 20
recvmsg(8, {msg_name(12)={sa_family=AF_NETLINK, pid=0, groups=00000000},
msg_iov(1)=[{"<\0\0\0\24\0\2\0
\16>F!\32\0\0\2\10\200\376\1\0\0\0\10"..., 4096}], msg_controllen=0,
msg_flags=0}, 0) = 128
recvmsg(8, {msg_name(12)={sa_family=AF_NETLINK, pid=0, groups=00000000},
msg_iov(1)=[{"@\0\0\0\24\0\2\0
\16>F!\32\0\0\n\200\200\376\1\0\0\0\24"..., 4096}], msg_controllen=0,
msg_flags=0}, 0) = 128
recvmsg(8, {msg_name(12)={sa_family=AF_NETLINK, pid=0, groups=00000000},
msg_iov(1)=[{"\24\0\0\0\3\0\2\0
\16>F!\32\0\0\0\0\0\0\1\0\0\0\24\0\1"..., 4096}], msg_controllen=0,
msg_flags=0}, 0) = 20
close(8)                                = 0
rt_sigaction(SIGTERM, {0x435870, [], SA_RESTORER|SA_RESTART,
0x2b20f9e49ca0}, NULL, 8) = 0
rt_sigaction(SIGINT, {0x435870, [], SA_RESTORER|SA_RESTART,
0x2b20f9e49ca0}, NULL, 8) = 0
rt_sigaction(SIGHUP, {0x435870, [], SA_RESTORER|SA_RESTART,
0x2b20f9e49ca0}, NULL, 8) = 0
time(NULL)                              = 1178471968
open("/etc/hosts.allow", O_RDONLY)      = 8
fstat(8, {st_mode=S_IFREG|0644, st_size=698, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0)
= 0x2b20fb119000
read(8, "# /etc/hosts.allow: list of host"..., 4096) = 698
close(8)                                = 0
munmap(0x2b20fb119000, 4096)            = 0
time(NULL)                              = 1178471968
--- SIGSEGV (Segmentation fault) @ 0 (0) ---
+++ killed by SIGSEGV +++
Process 6689 detached

I have tried to add "gdm: 192.168.0.0/20" to /etc/hosts.allow, to be
sure...

Regards
Sylvain Le Gall