Greg KH, le sam. 03 févr. 2024 16:03:20 -0800, a ecrit:
> On Sun, Feb 04, 2024 at 12:36:00AM +0100, Samuel Thibault wrote:
> > When userland echoes 8bit characters to /dev/synth with e.g.
> >
> > echo -e '\xe9' > /dev/synth
> >
> > synth_write would get characters beyond 0x7f, and thus negative when
> > char is signed. When given to synth_buffer_add which takes a u16, this
> > would sign-extend and produce a U+ffxy character rather than U+xy.
> > Users thus get garbled text instead of accents in their output.
> >
> > Let's fix this by making sure that we read unsigned characters.
> >
> > Signed-off-by: Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>
> > Fixes: 89fc2ae80bb1 ("speakup: extend synth buffer to 16bit unicode characters")
> > Cc: stable@xxxxxxxxxxxxxxx
> >
> > ---
> > drivers/accessibility/speakup/synth.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > --- a/drivers/accessibility/speakup/synth.c
> > +++ b/drivers/accessibility/speakup/synth.c
> > @@ -208,8 +208,9 @@ void spk_do_flush(void)
> > wake_up_process(speakup_task);
> > }
> >
> > -void synth_write(const char *buf, size_t count)
> > +void synth_write(const char *_buf, size_t count)
> > {
> > + const unsigned char *buf = (const unsigned char *) _buf;
> > while (count--)
> > synth_buffer_add(*buf++);
> > synth_start();
>
> Nit, I think you need a blank line after the new variable definition.
Ok.
> And why can't we just change these to be u8 instead of "char"? Wouldn't
> that solve this issue overall better?
I was wondering, but an example of caller is synth_direct_store, which
calls string_unescape_any_inplace on the buffer, which does take a char*
and I guess won't change.
Samuel
