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* [Bug testsuite/26016] New: Bad mmap error check in coredump-filter.c / testsuite
@ 2020-05-20 13:10 hanno at hboeck dot de
  2020-05-20 14:41 ` [Bug testsuite/26016] " simark at simark dot ca
                   ` (4 more replies)
  0 siblings, 5 replies; 6+ messages in thread
From: hanno at hboeck dot de @ 2020-05-20 13:10 UTC (permalink / raw)
  To: gdb-prs

https://sourceware.org/bugzilla/show_bug.cgi?id=26016

            Bug ID: 26016
           Summary: Bad mmap error check in coredump-filter.c / testsuite
           Product: gdb
           Version: HEAD
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: testsuite
          Assignee: unassigned at sourceware dot org
          Reporter: hanno at hboeck dot de
  Target Milestone: ---

In coredump-filter.c [1] there is this code:

  void *ret = mmap (addr, size, prot, flags, fd, offset);

  assert (ret != NULL);

The mmap function never returns NULL, on errors it returns MAP_FAILED (or -1).
Thus this check is wrong and should probably be "ret != MAP_FAILED".

(Sidenote: asserts usually shouldn't be used for error checking, but this may
be a design decision due to this being a test suite.)

[1]
https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=gdb/testsuite/gdb.base/coredump-filter.c;h=f53a933a72545741094fc9549ff4411e3741adbe;hb=HEAD

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* [Bug testsuite/26016] Bad mmap error check in coredump-filter.c / testsuite
  2020-05-20 13:10 [Bug testsuite/26016] New: Bad mmap error check in coredump-filter.c / testsuite hanno at hboeck dot de
@ 2020-05-20 14:41 ` simark at simark dot ca
  2020-05-20 14:42 ` simark at simark dot ca
                   ` (3 subsequent siblings)
  4 siblings, 0 replies; 6+ messages in thread
From: simark at simark dot ca @ 2020-05-20 14:41 UTC (permalink / raw)
  To: gdb-prs

https://sourceware.org/bugzilla/show_bug.cgi?id=26016

Simon Marchi <simark at simark dot ca> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2020-05-20
                 CC|                            |simark at simark dot ca
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1

--- Comment #1 from Simon Marchi <simark at simark dot ca> ---
Thanks for the report.  Was this found using some static analysis tool, or you
just stumbled on it?

I'll also fix the spots that check against -1 to use MAP_FAILED.

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* [Bug testsuite/26016] Bad mmap error check in coredump-filter.c / testsuite
  2020-05-20 13:10 [Bug testsuite/26016] New: Bad mmap error check in coredump-filter.c / testsuite hanno at hboeck dot de
  2020-05-20 14:41 ` [Bug testsuite/26016] " simark at simark dot ca
@ 2020-05-20 14:42 ` simark at simark dot ca
  2020-05-20 14:51 ` cvs-commit at gcc dot gnu.org
                   ` (2 subsequent siblings)
  4 siblings, 0 replies; 6+ messages in thread
From: simark at simark dot ca @ 2020-05-20 14:42 UTC (permalink / raw)
  To: gdb-prs

https://sourceware.org/bugzilla/show_bug.cgi?id=26016

--- Comment #2 from Simon Marchi <simark at simark dot ca> ---
(In reply to Hanno Boeck from comment #0)
> (Sidenote: asserts usually shouldn't be used for error checking, but this
> may be a design decision due to this being a test suite.)

For test programs I think it's fine.

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* [Bug testsuite/26016] Bad mmap error check in coredump-filter.c / testsuite
  2020-05-20 13:10 [Bug testsuite/26016] New: Bad mmap error check in coredump-filter.c / testsuite hanno at hboeck dot de
  2020-05-20 14:41 ` [Bug testsuite/26016] " simark at simark dot ca
  2020-05-20 14:42 ` simark at simark dot ca
@ 2020-05-20 14:51 ` cvs-commit at gcc dot gnu.org
  2020-05-20 14:54 ` hanno at hboeck dot de
  2020-05-20 14:55 ` simark at simark dot ca
  4 siblings, 0 replies; 6+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2020-05-20 14:51 UTC (permalink / raw)
  To: gdb-prs

https://sourceware.org/bugzilla/show_bug.cgi?id=26016

--- Comment #3 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Simon Marchi <simark@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=41977d16e4ee5b9ad01abf2cfce6edbfb6d79541

commit 41977d16e4ee5b9ad01abf2cfce6edbfb6d79541
Author: Simon Marchi <simon.marchi@efficios.com>
Date:   Wed May 20 10:50:39 2020 -0400

    gdb/testsuite: check mmap ret val against MAP_FAILED

    Fixup a few spots in the testsuite that use mmap to consistently check
    the return value against MAP_FAILED.

    One spot in gdb.base/coredump-filter.c checked against NULL, that is
    wrong.  The other spots either didn't check, or checked against -1.
    MAP_FAILED has the value -1, at least on Linux, but it's better to check
    against the documented define.

    gdb/testsuite/ChangeLog:

            PR gdb/26016
            * gdb.base/coredump-filter.c (do_mmap): Check mmap ret val
            against MAP_FAILED.
            * gdb.base/coremaker.c (mmapdata): Likewise.
            * gdb.base/jit-reader-host.c (main): Likewise.
            * gdb.base/sym-file-loader.c (load): Likewise.
            (load_shlib): Likewise.

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* [Bug testsuite/26016] Bad mmap error check in coredump-filter.c / testsuite
  2020-05-20 13:10 [Bug testsuite/26016] New: Bad mmap error check in coredump-filter.c / testsuite hanno at hboeck dot de
                   ` (2 preceding siblings ...)
  2020-05-20 14:51 ` cvs-commit at gcc dot gnu.org
@ 2020-05-20 14:54 ` hanno at hboeck dot de
  2020-05-20 14:55 ` simark at simark dot ca
  4 siblings, 0 replies; 6+ messages in thread
From: hanno at hboeck dot de @ 2020-05-20 14:54 UTC (permalink / raw)
  To: gdb-prs

https://sourceware.org/bugzilla/show_bug.cgi?id=26016

--- Comment #4 from Hanno Boeck <hanno at hboeck dot de> ---
(In reply to Simon Marchi from comment #1)
> Thanks for the report.  Was this found using some static analysis tool, or
> you just stumbled on it?

So this is a very good question and the answer may surprise you :-)

I learned about this type of bug and I thought "I can write a trivial
shellscript to find these kinds of bugs". So if my 6 lines of bash count as a
static analysis tool then yes.

I plan to release it soon, I'll post a link.

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* [Bug testsuite/26016] Bad mmap error check in coredump-filter.c / testsuite
  2020-05-20 13:10 [Bug testsuite/26016] New: Bad mmap error check in coredump-filter.c / testsuite hanno at hboeck dot de
                   ` (3 preceding siblings ...)
  2020-05-20 14:54 ` hanno at hboeck dot de
@ 2020-05-20 14:55 ` simark at simark dot ca
  4 siblings, 0 replies; 6+ messages in thread
From: simark at simark dot ca @ 2020-05-20 14:55 UTC (permalink / raw)
  To: gdb-prs

https://sourceware.org/bugzilla/show_bug.cgi?id=26016

Simon Marchi <simark at simark dot ca> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #5 from Simon Marchi <simark at simark dot ca> ---
Well, it worked well enough to find one bug, thanks!

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end of thread, other threads:[~2020-05-20 14:55 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2020-05-20 13:10 [Bug testsuite/26016] New: Bad mmap error check in coredump-filter.c / testsuite hanno at hboeck dot de
2020-05-20 14:41 ` [Bug testsuite/26016] " simark at simark dot ca
2020-05-20 14:42 ` simark at simark dot ca
2020-05-20 14:51 ` cvs-commit at gcc dot gnu.org
2020-05-20 14:54 ` hanno at hboeck dot de
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