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fxprintf: Get rid of alloca

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Use a scratch_buffer rather than alloca/malloc to avoid potential stack
overflow.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
This commit is contained in:
Joe Simmons-Talbott 2023-08-15 14:28:25 +00:00
parent d6fe19facc
commit 892e125f1c
1 changed files with 6 additions and 8 deletions
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14
stdio-common/fxprintf.c
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@ -15,6 +15,7 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <scratch_buffer.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
@ -34,20 +35,18 @@ locked_vfxprintf (FILE *fp, const char *fmt, va_list ap,
wchar_t *wfmt;
mbstate_t mbstate;
int res;
int used_malloc = 0;
size_t len = strlen (fmt) + 1;
struct scratch_buffer buf;
scratch_buffer_init (&buf);
if (__glibc_unlikely (len > SIZE_MAX / sizeof (wchar_t)))
{
__set_errno (EOVERFLOW);
return -1;
}
if (__libc_use_alloca (len * sizeof (wchar_t)))
wfmt = alloca (len * sizeof (wchar_t));
else if ((wfmt = malloc (len * sizeof (wchar_t))) == NULL)
if (!scratch_buffer_set_array_size (&buf, sizeof (wchar_t), len))
return -1;
else
used_malloc = 1;
wfmt = buf.data;
memset (&mbstate, 0, sizeof mbstate);
res = __mbsrtowcs (wfmt, &fmt, len, &mbstate);
@ -55,8 +54,7 @@ locked_vfxprintf (FILE *fp, const char *fmt, va_list ap,
if (res != -1)
res = __vfwprintf_internal (fp, wfmt, ap, mode_flags);
if (used_malloc)
free (wfmt);
scratch_buffer_free (&buf);
return res;
}