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Bug 1777241 - glibc: z15 (s390x) strstr implementation can return incorrect result if search string cross page boundary
Summary: glibc: z15 (s390x) strstr implementation can return incorrect result if searc...
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 8
Classification: Red Hat
Component: glibc
Version: 8.1
Hardware: s390x
OS: Linux
high
urgent
Target Milestone: beta
: 8.2
Assignee: Florian Weimer
QA Contact: qe-baseos-tools-bugs
Zuzana Zoubkova
URL:
Whiteboard:
Depends On: 1659438
Blocks: 1711971 1776957 1777797
TreeView+ depends on / blocked
 
Reported: 2019-11-27 09:26 UTC by Florian Weimer
Modified: 2023-07-18 14:30 UTC (History)
10 users (show)

Fixed In Version: glibc-2.28-99.el8
Doc Type: Bug Fix
Doc Text:
.`strstr` no longer returns incorrect matches for a truncated pattern On certain IBM Z platforms (z15, previously known as arch13), the `strstr` function did not correctly update a CPU register when handling search patterns that cross a page boundary. As a consequence, `strstr` returned incorrect matches. This update fixes the problem, and as a result, `strstr` works as expected in the mentioned scenario.
Clone Of:
: 1777797 (view as bug list)
Environment:
Last Closed: 2020-04-28 16:50:25 UTC
Type: Bug
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
IBM Linux Technology Center 182598 0 None None None 2019-11-27 10:48:56 UTC
Red Hat Bugzilla 1659438 1 None None None 2023-07-18 14:30:35 UTC
Red Hat Product Errata RHSA-2020:1828 0 None None None 2020-04-28 16:50:36 UTC
Sourceware 25226 0 P2 RESOLVED strstr: Invalid result if needle crosses page on s390-z15 ifunc variant. 2021-01-18 00:13:34 UTC

Internal Links: 1659438

Description Florian Weimer 2019-11-27 09:26:54 UTC 
Quoting the upstream bug:

“
If the specified needle crosses a page-boundary, the s390-z15 ifunc variant of
strstr truncates the needle which results in invalid results.

Example:
needle = "Hello" <page-boundary> "World"
really used needle = "Hello"
haystack = "abc HelloBug def"
result = "HelloBug def"

This only happens if the needle before page-boundary contains 9 or less characters.
The s390-z15 ifunc variant of strstr was introduces in glibc 2.30.
”

This was introduced into Red Hat Enterprise Linux 8.1 via bug 1659438.
Comment 1 Florian Weimer 2019-11-27 09:30:49 UTC 
We will need QA assistance for testing the change on z15 hardware.  Cc:ing IBM.
Comment 3 Hanns-Joachim Uhl 2019-11-27 10:48:56 UTC 
(In reply to Florian Weimer from comment #1)
> We will need QA assistance for testing the change on z15 hardware.  Cc:ing
> IBM.
.
... yes, IBM will do fix verification ... setting OtherQA ...
Comment 4 IBM Bug Proxy 2019-11-27 11:50:22 UTC 
------- Comment From STLI.com 2019-11-27 06:49 EDT-------
Please backport the glibc-commit "S390: Fix handling of needles crossing a page in strstr z15 ifunc-variant. [BZ #25226]" to RHEL 8.1 (AND RHEL 8.2) as it is already released there:

-upstream-glibc/master: https://sourceware.org/git/?p=glibc.git;a=commit;h=bfdb731438206b0f70fe7afa890681155c30b419

-upstream-bugzilla: "Bug 25226 - strstr: Invalid result if needle crosses page on s390-z15 ifunc variant." (https://sourceware.org/bugzilla/show_bug.cgi?id=25226)

Yes, I can test an updated rpm on z15 hardware.
Comment 8 IBM Bug Proxy 2019-12-17 11:40:23 UTC 
------- Comment From STLI.com 2019-12-17 06:37 EDT-------
I've installed RHEL 8.2is2 with glibc 2.28-99.el8 package and verified that the patch is applied.
Thanks.
Comment 9 Sergey Kolosov 2020-01-07 08:26:39 UTC 
Set as verified based on https://bugzilla.redhat.com/show_bug.cgi?id=1777241#c8 and after sanity check
Comment 10 Florian Weimer 2020-01-17 12:20:18 UTC 
Upstream commit:

commit bfdb731438206b0f70fe7afa890681155c30b419
Author: Stefan Liebler <stli.com>
Date:   Wed Nov 27 12:35:40 2019 +0100

    S390: Fix handling of needles crossing a page in strstr z15 ifunc-variant. [BZ #25226]
    
    If the specified needle crosses a page-boundary, the s390-z15 ifunc variant of
    strstr truncates the needle which results in invalid results.
    
    This is fixed by loading the needle beyond the page boundary to v18 instead of v16.
    The bug is sometimes observable in test-strstr.c in check1 and check2 as the
    haystack and needle is stored on stack. Thus the needle can be on a page boundary.
    
    check2 is now extended to test haystack / needles located on stack, at end of page
    and on two pages.
    
    This bug was introduced with commit 6f47401bd5fc71209219779a0426170a9a7395b0
    ("S390: Add arch13 strstr ifunc variant.") and is already released in glibc 2.30.
Comment 15 errata-xmlrpc 2020-04-28 16:50:25 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.

https://access.redhat.com/errata/RHSA-2020:1828
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