[Bug math/16961] New: nan function incorrect handling of bad sequences

[Bug math/16961] New: nan function incorrect handling of bad sequences

[jsm28 at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16961

            Bug ID: 16961
           Summary: nan function incorrect handling of bad sequences
           Product: glibc
           Version: 2.19
            Status: NEW
          Severity: normal
          Priority: P2
         Component: math
          Assignee: unassigned at sourceware dot org
          Reporter: jsm28 at gcc dot gnu.org

The nan function does:

  if (tagp[0] != '\0')
    {
      char buf[6 + strlen (tagp)];
      sprintf (buf, "NAN(%s)", tagp);
      return strtod (buf, NULL);
    }

If the argument starts with an n-char-sequence, but is not one in its entirety,
the return value is determined by that n-char-sequence.  But according to ISO
C, "If tagp does not point to an n-char sequence or an empty string, the call
is equivalent to strtod("NAN", (char**) NULL).", so the initial characters
should have no effect on the return value.  The same applies to nanf and nanl.

(n-char-sequences are sequences of ASCII letters, digits and underscores.)

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[Bug math/16961] nan function incorrect handling of bad sequences

[schwab@linux-m68k.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16961

Andreas Schwab <schwab@linux-m68k.org> changed:

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

--- Comment #1 from Andreas Schwab <schwab@linux-m68k.org> ---
strtod will do the right thing by ignoring the non-n-char-sequence.

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[Bug math/16961] nan function incorrect handling of bad sequences

[jsm28 at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16961

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|INVALID                     |---

--- Comment #2 from Joseph Myers <jsm28 at gcc dot gnu.org> ---
We're talking about arguments such as "1)", where strtod sees an initial
substring "NAN(1)" of its argument "NAN(1))" and processes that (but the
semantics of the nan function mean the whole string should be ignored).

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[Bug math/16961] nan function incorrect handling of bad sequences

[schwab@linux-m68k.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16961

Andreas Schwab <schwab@linux-m68k.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|REOPENED                    |RESOLVED
         Resolution|---                         |INVALID

--- Comment #3 from Andreas Schwab <schwab@linux-m68k.org> ---
Still not a problem, since the bits of a bare NAN are not specified.

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[Bug math/16961] nan function incorrect handling of bad sequences

[jsm28 at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16961

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|INVALID                     |---

--- Comment #4 from Joseph Myers <jsm28 at gcc dot gnu.org> ---
As a matter of quality of implementation, strtod("NAN"), and everything
equivalent to it, should produce the (architecture-specific) default quiet NaN
rather than some other NaN.

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[Bug math/16961] nan function incorrect handling of bad sequences

[schwab@linux-m68k.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16961

Andreas Schwab <schwab@linux-m68k.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |enhancement

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[Bug math/16961] nan function incorrect handling of bad sequences

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16961

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
              Flags|                            |security-

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