| Summary: | Segmentation fault in sna_dri2_get_back() | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Product: | xorg | Reporter: | John Lindgren <john> | ||||||||||
| Component: | Driver/intel | Assignee: | Chris Wilson <chris> | ||||||||||
| Status: | RESOLVED FIXED | QA Contact: | Intel GFX Bugs mailing list <intel-gfx-bugs> | ||||||||||
| Severity: | blocker | ||||||||||||
| Priority: | highest | CC: | andyrtr, intel-gfx-bugs | ||||||||||
| Version: | unspecified | ||||||||||||
| Hardware: | x86-64 (AMD64) | ||||||||||||
| OS: | Linux (All) | ||||||||||||
| Whiteboard: | |||||||||||||
| i915 platform: | i915 features: | ||||||||||||
| Attachments: |
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Downstream bug report (there are a number of other backtraces, probably not all related): https://bugs.archlinux.org/task/41443 "SXX" also mentioned this crash on #dri-devel a while back: http://people.freedesktop.org/~cbrill/dri-log//dri-devel-2014-07-01.log http://pastebin.com/peiptrse A "p *info" would be useful. I can't spot a way for the info->cache to become invalid, so that opens up the field to memory corruption. If you could install valgrind and recompile with --enable-debug that may catch an assertion earlier. If you could run X under valgrind and see if that flags the error, most useful. info->cache does look like the pointers got corrupted somewhere. Also info->draw != draw. I will see about running X in Valgrind.
(gdb) print *info
$2 = {
draw = 0x173fbf0,
client = 0x174d220,
type = 24065488,
crtc = 0x1000000000,
pipe = 36000,
queued = 32,
event_complete = 0x38000000338,
event_data = 0x400,
front = 0x25900000258,
back = 0x2710000025b,
bo = 0x500000000,
chain = 0x17488d0,
cache = {
next = 0x32000000320,
prev = 0x38000000338
},
link = {
next = 0x40000000400,
prev = 0x25800000000
},
mode = 600
}
(gdb) print *draw
$4 = {
type = 0 '\000',
class = 1 '\001',
depth = 24 '\030',
bitsPerPixel = 32 ' ',
id = 161,
x = 0,
y = 0,
width = 1366,
height = 768,
pScreen = 0x11fb860,
serialNumber = 1951
}
(gdb) print *info->draw
$5 = {
type = 0 '\000',
class = 101 'e',
depth = 116 't',
bitsPerPixel = 1 '\001',
id = 0,
x = -29952,
y = 388,
width = 0,
height = 0,
pScreen = 0x16ef480,
serialNumber = 68719476736
}
Created attachment 105155 [details]
Valgrind log
Relevant portion of Valgrind log attached. Seems to be a use-after-free situation.
John, what git commit is that? I am puzzled by the free() from sna_mode_wakeup. Maybe we need "-O0 -g3"? It is from: http://xorg.freedesktop.org//archive/individual/driver/xf86-video-intel-2.99.914.tar.bz2 Plus three patches from Arch Linux: https://projects.archlinux.org/svntogit/packages.git/tree/trunk?h=packages/xf86-video-intel Will attach valgrind output with -O0, --malloc-fill=0xff, --free-fill=0xff shortly. Created attachment 105158 [details]
Clearer valgrind log
Created attachment 105160 [details] [review] Unhook event from draw list upon ClientGone Comment on attachment 105160 [details] [review] Unhook event from draw list upon ClientGone Review of attachment 105160 [details] [review]: ----------------------------------------------------------------- This seems to fix it. Thank you much! Thanks for the bug report and running valgrind for me! commit 12c051d5c673d79c16a3a1478c0977799484ca95 Author: Chris Wilson <chris@chris-wilson.co.uk> Date: Sat Aug 23 15:33:13 2014 +0100 sna/dri2: Unhook event from draw list upon client destruction When the client goes away, we need to free its events. However, we have to defer the freeing of any pending event (ones currently routed through the kernel) for those we need to remember to decouple the event from the Drawable's list before they are freed. Reported-by: John Lindgren <john.lindgren@aol.com> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=82979 Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> |
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Created attachment 105130 [details] Log The following crash occurs frequently when I'm logging in or out. I'm using XFCE with Compton as compositor. xorg.conf contains only the NoTrapSignals flag, everything is default settings. Dell Latitude E5530 Intel(R) Core(TM) i5-3210M CPU @ 2.50GHz Arch Linux x86_64 linux 3.16.1-1 xorg-server 1.16.0-6 xf86-video-intel 2.99.914-4 Log file is attached (from an older build than the backtrace below, but it's the same crash). Please let me know if there is any more info that would be useful. Core was generated by `/usr/bin/Xorg.bin :1 vt7'. Program terminated with signal SIGSEGV, Segmentation fault. #0 sna_dri2_get_back (info=0x1848b00, back=0x16ef3a0, draw=0x142d180, sna=0x7f7365a25000) at sna_dri2.c:164 164 if (c->bo && c->bo->scanout == 0) { (gdb) bt full #0 sna_dri2_get_back (info=0x1848b00, back=0x16ef3a0, draw=0x142d180, sna=0x7f7365a25000) at sna_dri2.c:164 c = 0x32000000320 bo = <optimized out> name = 0 reuse = true #1 sna_dri2_reuse_buffer (draw=0x142d180, buffer=0x16ef3a0) at sna_dri2.c:282 buffer = 0x16ef3a0 draw = 0x142d180 #2 0x0000000000562e73 in allocate_or_reuse_buffer (pDraw=0x142d180, ds=<optimized out>, pPriv=0x16eedd0, attachment=1, format=32, dimensions_match=<optimized out>, buffer=0x182e460) at dri2.c:483 No locals. #3 0x0000000000563cab in do_get_buffers (pDraw=0x20, width=0x556, height=0x300, attachments=0x182c4b4, count=25463640, out_count=0x1, has_format=1) at dri2.c:551 attachment = 1 pPriv = 0x0 buffers_changed = 0 #4 0x00000000005640db in DRI2GetBuffersWithFormat (pDraw=<optimized out>, width=<optimized out>, height=<optimized out>, attachments=<optimized out>, count=<optimized out>, out_count=<optimized out>) at dri2.c:668 No locals. #5 0x0000000000565b7b in ProcDRI2GetBuffersWithFormat (client=<optimized out>) at dri2ext.c:306 buffers = 0x0 status = 0 count = 154 pDrawable = 0x142d180 width = 8554624 height = 24045712 #6 ProcDRI2Dispatch (client=0x16ee890) at dri2ext.c:608 stuff = 0x182c4a0 #7 0x00000000004375c7 in Dispatch () at dispatch.c:432 clientReady = 0x16f0d30 result = <optimized out> client = 0x16ee890 nready = 0 icheck = 0x82cb00 <checkForInput> start_tick = 0 #8 0x000000000043b756 in dix_main (argc=3, argv=0x7fff76def158, envp=<optimized out>) at main.c:296 i = <optimized out> alwaysCheckForInput = {0, 1} #9 0x00007f7363d35000 in __libc_start_main () from /usr/lib/libc.so.6 No symbol table info available. #10 0x0000000000425bfe in _start () No symbol table info available.