Mailinglist Archive: opensuse-bugs (4644 mails)

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[Bug 1045340] groupwise segfaults on kernel-default-4.4.72-18.12.2 (regression from stack gap fix?)
  • From: bugzilla_noreply@xxxxxxxxxx
  • Date: Wed, 21 Jun 2017 17:20:03 +0000
  • Message-id: <bug-1045340-21960-mRFKplngJZ@http.bugzilla.suse.com/>
http://bugzilla.suse.com/show_bug.cgi?id=1045340
http://bugzilla.suse.com/show_bug.cgi?id=1045340#c8

--- Comment #8 from Vlastimil Babka <vbabka@xxxxxxxx> ---
(In reply to Andreas Stieger from comment #7)
(In reply to Vlastimil Babka from comment #6)
How exactly can I get the rpm?

I am using:

https://gwclient.innerweb.novell.com/
https://gwclient.innerweb.novell.com/client/gw802linuxclient.tar.gz

Thanks. I've run it under gdb and when it segfaulted, checked the
/proc/pid/smaps:

ffedd000-fffae000 rwxp 00000000 00:00 0 (this is without the gap)
Size: 1860 kB (the size however includes gap)
...
VmFlags: rd wr ex mr mw me gd ac (gd == grows down - a stack)
fffae000-fffb1000 ---p 00000000 00:00 0 (not r/w/x)
Size: 12 kB
...
VmFlags: mr mw me ac sd (doesn't have gd)
1000b1000-ffffe000 rwxp 00000000 00:00 0 (invalid reported start addr as it
adds the full gap size to real vma start) [stack]
Size: 308 kB (real size without gap:
fffb1000-ffffe000)
Rss: 24 kB (we have used only this much stack
yet)
Pss: 24 kB
Shared_Clean: 0 kB
Shared_Dirty: 0 kB
Private_Clean: 0 kB
Private_Dirty: 24 kB
Referenced: 24 kB
Anonymous: 24 kB
AnonHugePages: 0 kB
Shared_Hugetlb: 0 kB
Private_Hugetlb: 0 kB
Swap: 0 kB
SwapPss: 0 kB
KernelPageSize: 4 kB
MMUPageSize: 4 kB
Locked: 0 kB
VmFlags: rd wr ex mr mw me gd ac (again grows down)

Looks like the same issue as I've seen with jsvc reproducer from debian
bugzilla, that we discussed via mail. The original stack ffedd000-ffffe000 was
split by mprotecting the area
ffedd000-fffae000 inside the stack. The remaining "upper part"
fffb1000-ffffe000 is now smaller than stack gap, and preceding vma is not a
stack, so faulting a new page in the upper part (where we only have faulted in
24 kB so far) will find this out and fail to enlarge the gap, thus segfault.

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