From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: jobol@nonadev.net, libc-alpha@sourceware.org
Subject: Re: [PATCH] libio: Ensure output buffer for wchars (bug 28828)
Date: Mon, 14 Feb 2022 11:15:46 -0300 [thread overview]
Message-ID: <391bad58-2186-93db-c1bc-663e7fbe6345@linaro.org> (raw)
In-Reply-To: <d0de9746e5d0fef131a2c4fdc85bfbef@nonadev.net>
On 13/02/2022 16:52, jobol@nonadev.net wrote:
> When fileops.c checks for nullity of the write pointer,
> in order to ensure its allocation, before that patch,
> wfileops didn't. This was leading to crashes on some cases,
> as described by bug 28828.
>
> The minimal sequence to produce the crash was:
>
> #include <stdio.h>
> #include <wchar.h>
> int main(int ac, char **av)
> {
> setvbuf(stdout, NULL, _IOLBF, 0);
> fgetwc(stdin);
> fputwc(10, stdout); /*CRASH HERE!*/
> return 0;
> }
>
> The line "fgetwc(stdin);" is necessary. It introduces the
> bug by setting the flag _IO_CURRENTLY_PUTTING of stdout
> indirectly (file wfileops.c, function _IO_wfile_underflow, line 213).
>
> Signed-off-by: Jose Bollo <jobol@nonadev.net>
Patch looks ok, but git-pw fails to apply it:
$ git-pw patch apply 51088
Applying: libio: Ensure output buffer for wchars (bug 28828)
error: patch failed: libio/wfileops.c:412
error: libio/wfileops.c: patch does not apply
error: Did you hand edit your patch?
Could you resend it?
Also, could you also provide a regression testcase for this fix?
> ---
> libio/wfileops.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/libio/wfileops.c b/libio/wfileops.c
> index fb9d45b677..aa94a22983 100644
> --- a/libio/wfileops.c
> +++ b/libio/wfileops.c
> @@ -412,10 +412,11 @@ _IO_wfile_overflow (FILE *f, wint_t wch)
> return WEOF;
> }
> /* If currently reading or no buffer allocated. */
> - if ((f->_flags & _IO_CURRENTLY_PUTTING) == 0)
> + if ((f->_flags & _IO_CURRENTLY_PUTTING) == 0
> + || f->_wide_data->_IO_write_base == NULL)
> {
> /* Allocate a buffer if needed. */
> - if (f->_wide_data->_IO_write_base == 0)
> + if (f->_wide_data->_IO_write_base == NULL)
> {
> _IO_wdoallocbuf (f);
> _IO_free_wbackup_area (f);
next prev parent reply other threads:[~2022-02-14 14:15 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-13 19:52 jobol
2022-02-14 14:15 ` Adhemerval Zanella [this message]
2022-02-14 18:10 ` José Bollo
2022-02-14 18:37 ` Adhemerval Zanella
2022-02-14 20:23 José Bollo
2022-02-21 19:14 ` Adhemerval Zanella
2022-02-22 20:55 [PATCH v3] " jobol
2022-03-08 8:54 ` [PATCH] " jobol
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