[Bug libc/18887] New: memory corruption when using getmntent on blank lines

[Bug libc/18887] New: memory corruption when using getmntent on blank lines

[vapier at gentoo dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=18887

            Bug ID: 18887
           Summary: memory corruption when using getmntent on blank lines
           Product: glibc
           Version: 2.23
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
          Assignee: unassigned at sourceware dot org
          Reporter: vapier at gentoo dot org
                CC: drepper.fsp at gmail dot com
        Depends on: 17273
  Target Milestone: ---

the change introduced in bug 17273 ends up corrupting memory by a single byte
when processing lines that are all whitespace.  this can go unnoticed on many
arches, but it seems to trigger frequently on ppc32.

$ cat > test.c <<EOF
#include <mntent.h>
int main(void) {
        FILE *fp = setmntent("/etc/fstab", "r");
        getmntent(fp);
        endmntent(fp);
}
EOF

$ gcc test.c
$ ./a.out
*** Error in `./a.out': double free or corruption (!prev): 0x10021008 ***
======= Backtrace: =========
/lib/libc.so.6(+0x7bcac)[0xfef2cac]
/lib/libc.so.6(+0x83314)[0xfefa314]
/lib/libc.so.6(+0x84270)[0xfefb270]
/lib/libc.so.6(fclose+0x1e8)[0xfee5838]
/lib/libc.so.6(endmntent+0x2c)[0xff5e11c]
/lib/libc.so.6(+0x21b38)[0xfe98b38]
/lib/libc.so.6(+0x21cd8)[0xfe98cd8]


Referenced Bugs:

https://sourceware.org/bugzilla/show_bug.cgi?id=17273
[Bug 17273] getmntent() returns wrong default value for fs_passno
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[Bug libc/18887] memory corruption when using getmntent on blank lines

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=18887

--- Comment #1 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
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https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=b0e805fa0d6fea33745952df7b7f5442ca4c374f

commit b0e805fa0d6fea33745952df7b7f5442ca4c374f
Author: Mike Frysinger <vapier@gentoo.org>
Date:   Fri Aug 28 17:08:49 2015 -0400

    getmntent: fix memory corruption w/blank lines [BZ #18887]

    The fix for BZ #17273 introduced a single byte of memory corruption when
    the line is entirely blank.  It would walk back past the start of the
    buffer if the heap happened to be 0x20 or 0x09 and then write a NUL byte.
        buffer = '\n';
        end_ptr = buffer;
        while (end_ptr[-1] == ' ' || end_ptr[-1] == '\t')
                end_ptr--;
        *end_ptr = '\0';

    Fix that and rework the tests.  Adding the testcase for BZ #17273 to the
    existing \040 parser does not really make sense as it's unrelated, and
    leads to confusing behavior: it implicitly relies on the new entry being
    longer than the previous entry (since it just rewinds the FILE*).  Split
    it out into its own dedicated testcase instead.

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog                                          |   10 +++++
 misc/Makefile                                      |    3 +-
 misc/mntent_r.c                                    |    4 +-
 .../tst-mntent-blank-corrupt.c                     |   43 ++++++++-----------
 .../tst-mntent-blank-passno.c                      |   40 ++++++++++--------
 misc/tst-mntent.c                                  |   20 ---------
 6 files changed, 55 insertions(+), 65 deletions(-)
 copy posix/bug-regex35.c => misc/tst-mntent-blank-corrupt.c (60%)
 copy math/tst-definitions.c => misc/tst-mntent-blank-passno.c (55%)

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[Bug libc/18887] memory corruption when using getmntent on blank lines

[vapier at gentoo dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=18887

Mike Frysinger <vapier at gentoo dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
           See Also|                            |https://bugs.gentoo.org/sho
                   |                            |w_bug.cgi?id=558946
         Resolution|---                         |FIXED

--- Comment #2 from Mike Frysinger <vapier at gentoo dot org> ---
fixed by that commit

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[Bug libc/18887] memory corruption when using getmntent on blank lines

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=18887

--- Comment #3 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
This is an automated email from the git hooks/post-receive script. It was
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The branch, release/2.21/master has been updated
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      from  978908245b2c0f759100708a9966649f7b273664 (commit)

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https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=f2cdbadd8a078482d3b9fc2b59e888c64cc4efae

commit f2cdbadd8a078482d3b9fc2b59e888c64cc4efae
Author: Mike Frysinger <vapier@gentoo.org>
Date:   Fri Aug 28 17:08:49 2015 -0400

    getmntent: fix memory corruption w/blank lines [BZ #18887]

    The fix for BZ #17273 introduced a single byte of memory corruption when
    the line is entirely blank.  It would walk back past the start of the
    buffer if the heap happened to be 0x20 or 0x09 and then write a NUL byte.
        buffer = '\n';
        end_ptr = buffer;
        while (end_ptr[-1] == ' ' || end_ptr[-1] == '\t')
                end_ptr--;
        *end_ptr = '\0';

    Fix that and rework the tests.  Adding the testcase for BZ #17273 to the
    existing \040 parser does not really make sense as it's unrelated, and
    leads to confusing behavior: it implicitly relies on the new entry being
    longer than the previous entry (since it just rewinds the FILE*).  Split
    it out into its own dedicated testcase instead.

    (cherry picked from commit b0e805fa0d6fea33745952df7b7f5442ca4c374f)

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog                                          |   10 +++++
 NEWS                                               |    2 +-
 misc/Makefile                                      |    3 +-
 misc/mntent_r.c                                    |    4 +-
 .../tst-mntent-blank-corrupt.c                     |   27 +++++++------
 .../tst-mntent-blank-passno.c                      |   40 +++++++++++---------
 misc/tst-mntent.c                                  |   20 ----------
 7 files changed, 53 insertions(+), 53 deletions(-)
 copy libio/test-fmemopen.c => misc/tst-mntent-blank-corrupt.c (60%)
 copy math/tst-definitions.c => misc/tst-mntent-blank-passno.c (55%)

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[Bug libc/18887] memory corruption when using getmntent on blank lines

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=18887

--- Comment #4 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
This is an automated email from the git hooks/post-receive script. It was
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The branch, release/2.22/master has been updated
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      from  64c25345714d792b283c8c8469d58f898d1ef109 (commit)

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https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=3007f797a1a596e954f44879a5a7267966186ba4

commit 3007f797a1a596e954f44879a5a7267966186ba4
Author: Mike Frysinger <vapier@gentoo.org>
Date:   Fri Aug 28 17:08:49 2015 -0400

    getmntent: fix memory corruption w/blank lines [BZ #18887]

    The fix for BZ #17273 introduced a single byte of memory corruption when
    the line is entirely blank.  It would walk back past the start of the
    buffer if the heap happened to be 0x20 or 0x09 and then write a NUL byte.
        buffer = '\n';
        end_ptr = buffer;
        while (end_ptr[-1] == ' ' || end_ptr[-1] == '\t')
                end_ptr--;
        *end_ptr = '\0';

    Fix that and rework the tests.  Adding the testcase for BZ #17273 to the
    existing \040 parser does not really make sense as it's unrelated, and
    leads to confusing behavior: it implicitly relies on the new entry being
    longer than the previous entry (since it just rewinds the FILE*).  Split
    it out into its own dedicated testcase instead.

    (cherry picked from commit b0e805fa0d6fea33745952df7b7f5442ca4c374f)

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog                                          |   10 +++++
 NEWS                                               |    2 +-
 misc/Makefile                                      |    3 +-
 misc/mntent_r.c                                    |    4 +-
 .../tst-mntent-blank-corrupt.c                     |   43 ++++++++-----------
 .../tst-mntent-blank-passno.c                      |   40 ++++++++++--------
 misc/tst-mntent.c                                  |   20 ---------
 7 files changed, 56 insertions(+), 66 deletions(-)
 copy posix/bug-regex35.c => misc/tst-mntent-blank-corrupt.c (60%)
 copy math/tst-definitions.c => misc/tst-mntent-blank-passno.c (55%)

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[Bug libc/18887] memory corruption when using getmntent on blank lines

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=18887

--- Comment #5 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
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The branch, gentoo/2.21 has been updated
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      from  43d7ce9238c59c61003994cb26eff4a6a072ebd5 (commit)

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commit 460e5da421067eb690ba3b9d11183c4b7db37e4f
Author: Mike Frysinger <vapier@gentoo.org>
Date:   Fri Aug 28 17:08:49 2015 -0400

    getmntent: fix memory corruption w/blank lines [BZ #18887]

    The fix for BZ #17273 introduced a single byte of memory corruption when
    the line is entirely blank.  It would walk back past the start of the
    buffer if the heap happened to be 0x20 or 0x09 and then write a NUL byte.
        buffer = '\n';
        end_ptr = buffer;
        while (end_ptr[-1] == ' ' || end_ptr[-1] == '\t')
                end_ptr--;
        *end_ptr = '\0';

    Fix that and rework the tests.  Adding the testcase for BZ #17273 to the
    existing \040 parser does not really make sense as it's unrelated, and
    leads to confusing behavior: it implicitly relies on the new entry being
    longer than the previous entry (since it just rewinds the FILE*).  Split
    it out into its own dedicated testcase instead.

    (cherry picked from commit b0e805fa0d6fea33745952df7b7f5442ca4c374f)
    (cherry picked from commit f2cdbadd8a078482d3b9fc2b59e888c64cc4efae)

-----------------------------------------------------------------------

Summary of changes:
 misc/Makefile                                      |    3 +-
 misc/mntent_r.c                                    |    4 +-
 .../tst-mntent-blank-corrupt.c                     |   27 +++++++------
 .../tst-mntent-blank-passno.c                      |   40 +++++++++++---------
 misc/tst-mntent.c                                  |   20 ----------
 5 files changed, 42 insertions(+), 52 deletions(-)
 copy libio/test-fmemopen.c => misc/tst-mntent-blank-corrupt.c (60%)
 copy math/tst-definitions.c => misc/tst-mntent-blank-passno.c (55%)

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[Bug libc/18887] memory corruption when using getmntent on blank lines

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=18887

--- Comment #6 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
This is an automated email from the git hooks/post-receive script. It was
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The branch, gentoo/2.22 has been updated
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commit ca6a9ce6151759981cc2efd58e053148c7db2fea
Author: Mike Frysinger <vapier@gentoo.org>
Date:   Fri Aug 28 17:08:49 2015 -0400

    getmntent: fix memory corruption w/blank lines [BZ #18887]

    The fix for BZ #17273 introduced a single byte of memory corruption when
    the line is entirely blank.  It would walk back past the start of the
    buffer if the heap happened to be 0x20 or 0x09 and then write a NUL byte.
        buffer = '\n';
        end_ptr = buffer;
        while (end_ptr[-1] == ' ' || end_ptr[-1] == '\t')
                end_ptr--;
        *end_ptr = '\0';

    Fix that and rework the tests.  Adding the testcase for BZ #17273 to the
    existing \040 parser does not really make sense as it's unrelated, and
    leads to confusing behavior: it implicitly relies on the new entry being
    longer than the previous entry (since it just rewinds the FILE*).  Split
    it out into its own dedicated testcase instead.

    (cherry picked from commit b0e805fa0d6fea33745952df7b7f5442ca4c374f)
    (cherry picked from commit 3007f797a1a596e954f44879a5a7267966186ba4)

-----------------------------------------------------------------------

Summary of changes:
 misc/Makefile                                      |    3 +-
 misc/mntent_r.c                                    |    4 +-
 .../tst-mntent-blank-corrupt.c                     |   43 ++++++++-----------
 .../tst-mntent-blank-passno.c                      |   40 ++++++++++--------
 misc/tst-mntent.c                                  |   20 ---------
 5 files changed, 45 insertions(+), 65 deletions(-)
 copy posix/bug-regex35.c => misc/tst-mntent-blank-corrupt.c (60%)
 copy math/tst-definitions.c => misc/tst-mntent-blank-passno.c (55%)

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[Bug libc/18887] memory corruption when using getmntent on blank lines

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=18887

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |fweimer at redhat dot com

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[Bug libc/18887] memory corruption when using getmntent on blank lines

[jsm28 at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=18887

Joseph Myers <jsm28 at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |2.23

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