Bug 1317869 - Xephyr crashes when launched over ssh X forwarding from Windows
Summary: Xephyr crashes when launched over ssh X forwarding from Windows
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: xorg-x11-server
Version: 7.2
Hardware: x86_64
OS: All
Target Milestone: rc
: ---
Assignee: Adam Jackson
QA Contact: Desktop QE
Depends On:
Blocks: 1374198
TreeView+ depends on / blocked
Reported: 2016-03-15 12:06 UTC by Ashish Shah
Modified: 2016-11-04 02:50 UTC (History)
4 users (show)

Clone Of:
: 1374198 (view as bug list)
Last Closed: 2016-11-04 02:50:57 UTC

Attachments (Terms of Use)

External Trackers
Tracker ID Priority Status Summary Last Updated
Red Hat Product Errata RHBA-2016:2293 normal SHIPPED_LIVE X.Org X11 server and drivers bug fix and enhancement update 2016-11-03 13:38:01 UTC

Description Ashish Shah 2016-03-15 12:06:09 UTC
Description of problem:

Xephyr crashes with below backtrace when launched over ssh X forwarded session from Windows.

Xephyr unable to use SHM XImages
(EE) Backtrace:
(EE) 0: Xephyr (xorg_backtrace+0x55) [0x5af7b5]
(EE) 1: Xephyr (0x400000+0x1b3669) [0x5b3669]
(EE) 2: /lib64/libpthread.so.0 (0x7f2963ff3000+0xf100) [0x7f2964002100]
(EE) 3: /lib64/libxcb-xv.so.0 (xcb_xv_query_adaptors_info_iterator+0x0) [0x7f29627ad050]
(EE) 4: Xephyr (0x400000+0x310fb) [0x4310fb]
(EE) 5: Xephyr (0x400000+0x2b34d) [0x42b34d]
(EE) 6: Xephyr (0x400000+0xaf25b) [0x4af25b]
(EE) 7: Xephyr (AddScreen+0x71) [0x472971]
(EE) 8: Xephyr (0x400000+0xaf729) [0x4af729]
(EE) 9: Xephyr (0x400000+0x7644b) [0x47644b]
(EE) 10: /lib64/libc.so.6 (__libc_start_main+0xf5) [0x7f2960d39b15]
(EE) 11: Xephyr (0x400000+0x2a039) [0x42a039]
(EE) Segmentation fault at address 0x8
Fatal server error:
(EE) Caught signal 11 (Segmentation fault). Server aborting

Version-Release number of selected component (if applicable):
mobaXterm-8.6 on Windows
How reproducible:

Steps to Reproduce:
1. Login to rhel7 over ssh using mobaXterm from Windows
2. Launch Xephyr
 Xephyr :1

Actual results:

Expected results:
no crash

Additional info:
Launch of Xephyr with -noxv option helps to workaround this issue.

Comment 1 Ashish Shah 2016-03-15 12:07:19 UTC
Program terminated with signal 11, Segmentation fault.
#0  xcb_xv_query_adaptors_info_iterator (R=R@entry=0x0) at xv.c:690
690	    return i;
(gdb) t a a bt full

Thread 1 (Thread 0x7f30ad7cfa00 (LWP 21497)):
#0  xcb_xv_query_adaptors_info_iterator (R=R@entry=0x0) at xv.c:690
No locals.
#1  0x00000000004310fb in ephyrXVPrivQueryHostAdaptors (a_this=0x22e0150) at ephyrvideo.c:482
        conn = <optimized out>
        i = 0
        is_ok = 0
        e = 0x0
        xscreen = 0x22d53f8
        base_port_id = 0
        port_priv_offset = 0
        it = {data = 0x0, rem = 0, index = 0}
#2  ephyrXVPrivNew () at ephyrvideo.c:260
        xv_priv = 0x22e0150
#3  ephyrInitVideo (pScreen=0x22de060) at ephyrvideo.c:230
        screen = <optimized out>
        xv_priv = 0x0
#4  0x000000000042b34d in ephyrInitScreen (pScreen=0x22de060) at ephyr.c:664
        screen = 0x22ce5d0
#5  0x00000000004af25b in KdScreenInit (pScreen=pScreen@entry=0x22de060, argc=argc@entry=2, 
    argv=argv@entry=0x7ffff56f26d8) at kdrive.c:901
        screen = 0x22ce5d0
        card = 0x22ce590
        rotated = <optimized out>
        width = 640
        height = 480
        width_mmp = 0x22ce608
        height_mmp = 0x22ce60c
#6  0x0000000000472971 in AddScreen (pfnInit=pfnInit@entry=0x4af040 <KdScreenInit>, 
    argc=argc@entry=2, argv=argv@entry=0x7ffff56f26d8) at dispatch.c:3866
        i = 0
        pScreen = 0x22de060
        ret = <optimized out>
#7  0x00000000004af729 in KdAddScreen (argv=<optimized out>, argc=<optimized out>, 
    screen=<optimized out>, pScreenInfo=<optimized out>) at kdrive.c:1062
        i = <optimized out>
#8  KdInitOutput (pScreenInfo=pScreenInfo@entry=0x86e320 <screenInfo>, argc=argc@entry=2, 
    argv=argv@entry=0x7ffff56f26d8) at kdrive.c:1125
        card = 0x22ce590
        screen = 0x22ce5d0
#9  0x000000000042ce37 in InitOutput (pScreenInfo=pScreenInfo@entry=0x86e320 <screenInfo>, 
    argc=argc@entry=2, argv=argv@entry=0x7ffff56f26d8) at ephyrinit.c:88
No locals.
#10 0x000000000047644b in dix_main (argc=2, argv=0x7ffff56f26d8, envp=<optimized out>)
    at main.c:202
        i = <optimized out>
        alwaysCheckForInput = {0, 1}
#11 0x00007f30a8aaeb15 in __libc_start_main (main=0x429fe0 <main>, argc=2, 
    ubp_av=0x7ffff56f26d8, init=<optimized out>, fini=<optimized out>, 
    rtld_fini=<optimized out>, stack_end=0x7ffff56f26c8) at libc-start.c:274
        result = <optimized out>
        unwind_buf = {cancel_jmp_buf = {{jmp_buf = {0, -5180591105851376941, 4366352, 
                140737311090384, 0, 0, 5180614051418225363, 5078800904215608019}, 
              mask_was_saved = 0}}, priv = {pad = {0x0, 0x0, 0x5c0b80 <__libc_csu_init>, 
              0x7ffff56f26d8}, data = {prev = 0x0, cleanup = 0x0, canceltype = 6032256}}}
        not_first_call = <optimized out>
#12 0x000000000042a039 in _start ()
No symbol table info available.

Comment 2 Ashish Shah 2016-03-15 12:20:32 UTC
Could there be any problem from X server side? or can we handle it to terminate with appropriate error instead of crash?
I checked on Fedora 23 and same is the case there with xorg-x11-server-Xephyr-1.18.1-3.fc23.x86_64

Comment 3 Adam Jackson 2016-07-05 17:04:07 UTC
Oh that's cute. Your X server supports the XVIDEO extension, but lists no adaptors. Out of curiosity, which X server are you using on Windows, and what does "xvinfo" print in this situation?

Comment 6 Mayur 2016-07-15 10:23:34 UTC
Customer wants an update on this bz soon as they want to rollout a few servers using Xephyr in autumn and won't use the workaround permanently.

Comment 7 Adam Jackson 2016-07-20 16:36:28 UTC
It's a bug in Xephyr. I've sent a patch for it upstream:


I expect this to be fixed in 7.3, just waiting on acks.

Comment 15 errata-xmlrpc 2016-11-04 02:50:57 UTC
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.


Note You need to log in before you can comment on or make changes to this bug.