Bug 732857 - "__libc_res_nquery: Assertion `hp != hp2' failed." crashes many apps on particular failed DNS queries
"__libc_res_nquery: Assertion `hp != hp2' failed." crashes many apps on parti...
Status: CLOSED DUPLICATE of bug 730856
Product: Fedora
Classification: Fedora
Component: glibc (Show other bugs)
Unspecified Unspecified
unspecified Severity urgent
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Assigned To: Andreas Schwab
Fedora Extras Quality Assurance
Depends On:
Blocks: F16Beta-accepted/F16BetaFreezeExcept F16Blocker/F16FinalBlocker
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Reported: 2011-08-23 19:38 EDT by Adam Williamson
Modified: 2016-11-24 10:36 EST (History)
3 users (show)

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Fixed In Version:
Doc Type: Bug Fix
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Last Closed: 2011-08-23 19:41:26 EDT
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Attachments (Terms of Use)
Proposed fix (from Aurelien Jarno, Debian) (1.80 KB, patch)
2011-08-23 19:39 EDT, Adam Williamson
no flags Details | Diff

  None (edit)
Description Adam Williamson 2011-08-23 19:38:27 EDT
As discussed in various places - devel list, https://bugs.archlinux.org/task/24615 , and http://sourceware.org/bugzilla/show_bug.cgi?id=13013 - current glibc contains a bug which can cause any app to crash if a DNS lookup fails in a particular way (so far as I can tell). Usually the bug is hard to reliably reproduce - just trying to browse to a garbage domain doesn't do it - but https://bugs.archlinux.org/task/24615#comment78282 claims this as a reliable reproducer:

# iptables -A OUTPUT -p udp --dport 53 -j REJECT --reject-with icmp-admin-prohibited
# wget http://google.com/
--2011-06-08 12:13:58-- http://google.com/
Resolving google.com... zsh: segmentation fault (core dumped)

http://sourceware.org/bugzilla/show_bug.cgi?id=13013 has a proposed patch, which I will attach to this report. Kevin Fenzi did a scratch build - http://koji.fedoraproject.org/koji/taskinfo?taskID=3289243 - with the patch, which he says seems to resolve the issue for him. That report also suggests that the condition to cause the crash is "When the first answer is a SERVFAIL, NOTIMP or REFUSED".
Comment 1 Adam Williamson 2011-08-23 19:39:15 EDT
Created attachment 519536 [details]
Proposed fix (from Aurelien Jarno, Debian)
Comment 2 Adam Williamson 2011-08-23 19:40:05 EDT
proposing as Beta NTH and final release blocker, this is a bit icky of a bug to ship with.
Comment 3 Adam Williamson 2011-08-23 19:41:26 EDT
holy cow, it's groundhog day. I already reported this one and promptly forgot. sigh.

*** This bug has been marked as a duplicate of bug 730856 ***

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