GNU bug report logs - #27838
grep error: "regexec.c:1375: pop_fail_stack: Assertion `num >= 0' failed."

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Jacek Wielemborek <d33tah <at> gmail.com>
To: bug-coreutils <at> gnu.org
Subject: grep error: "regexec.c:1375: pop_fail_stack: Assertion `num >= 0'
 failed."
Date: Wed, 26 Jul 2017 16:53:07 +0200

Hi,

Try out the following test case, IIRC found with the aid of afl-fuzz:

grep -E -f <( echo
'fzJ7fymOjgqOjgkfMnt/KSgfVzN8pFyQKR8zfGR7pGuQKR8zfCh8Mnt/KSgfVzN8pFyQKR8zfGR7pGuQKR8zfGR7kCkoCx8zfDJ7fymOrQmOjgkfM3wkXDI='
| base64 -d ) /dev/null
grep: regexec.c:1375: pop_fail_stack: Assertion `num >= 0' failed.

I reported it once as on Fedora's Bugzilla, but got no reaction - in
that case it even triggered a segmentation fault.

Cheers,
d33tah

Message #10 received at 27838-done <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Jacek Wielemborek <d33tah <at> gmail.com>, 27838-done <at> debbugs.gnu.org
Subject: Re: bug#27838: grep error: "regexec.c:1375: pop_fail_stack: Assertion
 `num >= 0' failed."
Date: Wed, 26 Jul 2017 09:24:59 -0700

[Message part 1 (text/plain, inline)]

Thanks, that is due to an already known bug in glibc; see:

https://sourceware.org/bugzilla/show_bug.cgi?id=18986
https://debbugs.gnu.org/21513

To work around the problem with grep, use './configure --with-included-regex' 
when building grep, or encourage your upstream distributor to do so (or better 
yet, to fix glibc). You might also follow up on the glibc bug report to mention 
that the problem affects you too.

In the meantime I installed the attached patch, to add your test case to grep's 
test suite. The test is expected to fail if glibc regex is used.

[0001-tests-add-Bug-27838-test-case.patch (text/x-patch, attachment)]

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