Re: [PATCH v5] newlib: libc: Fix crash on fprintf to a wide-oriented stream.

[Takashi Yano <takashi.yano@nifty.ne.jp>]

On Thu, 9 Nov 2023 11:08:03 +0100
Corinna Vinschen wrote:
> On Nov  9 06:48, Takashi Yano wrote:
> > Previously, fprintf() on a wide-oriented stream crashes or outputs
> > garbage. This is because a narrow char string which can be odd bytes
> > in length is cast into a wide char string which should be even
> > bytes in length in __sprint_r/__sfputs_r based on the __SWID flag.
> > As a result, if the length is odd bytes, the reading buffer runs over
> > the buffer length, which causes a crash. If the length is even bytes,
> > garbage is printed.
> > 
> > With this patch, any output to the stream which is set to different
> > orientation fails with error just like glibc. Note that it behaves
> > differently from other libc implementations such as BSD, musl and
> > Solaris.
> > 
> > Reviewed-by: Corinna Vinschen <corinna@vinschen.de>
> > Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>
> > ---
> >  newlib/libc/stdio/fgetwc.c    |  6 ++++--
> >  newlib/libc/stdio/fgetwc_u.c  |  3 ++-
> >  newlib/libc/stdio/fgetws.c    |  3 ++-
> >  newlib/libc/stdio/fputs.c     |  9 ++++++---
> >  newlib/libc/stdio/fputwc.c    |  6 ++++--
> >  newlib/libc/stdio/fputwc_u.c  |  3 ++-
> >  newlib/libc/stdio/fputws.c    |  6 ++++--
> >  newlib/libc/stdio/fread.c     |  7 ++++++-
> >  newlib/libc/stdio/fwrite.c    |  9 +++++++--
> >  newlib/libc/stdio/local.h     | 31 +++++++++++++++++--------------
> >  newlib/libc/stdio/putc.c      |  4 ++++
> >  newlib/libc/stdio/puts.c      |  9 ++++++---
> >  newlib/libc/stdio/refill.c    |  3 ++-
> >  newlib/libc/stdio/ungetc.c    |  6 +++++-
> >  newlib/libc/stdio/ungetwc.c   |  5 +++--
> >  newlib/libc/stdio/vfprintf.c  |  5 ++++-
> >  newlib/libc/stdio/vfscanf.c   |  6 +++++-
> >  newlib/libc/stdio/vfwprintf.c |  5 ++++-
> >  newlib/libc/stdio/vfwscanf.c  |  6 +++++-
> >  19 files changed, 92 insertions(+), 40 deletions(-)
> 
> Looks good, please push.

Thanks. Should this also be applied to cygwin-3_4-branch?

-- 
Takashi Yano <takashi.yano@nifty.ne.jp>