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From 79b2667d1eb06c6503c22f2f323c1c574ac5917b Mon Sep 17 00:00:00 2001
From: Joe Simmons-Talbott <josimmon@redhat.com>
Date: Tue, 23 May 2023 15:41:29 -0400
Subject: [PATCH] time: strftime_l: Avoid an unbounded alloca.
Avoid possible stack overflow by removing alloca() and converting to
wide characters within the buffer.
Conflict: NA
Reference: https://sourceware.org/git/?p=glibc.git;a=commit;h=79b2667d1eb06c6503c22f2f323c1c574ac5917b
Suggested-by: Paul Eggert <eggert@cs.ucla.edu>
---
time/strftime_l.c | 39 +++++++++++++++++++++++++--------------
1 file changed, 25 insertions(+), 14 deletions(-)
diff --git a/time/strftime_l.c b/time/strftime_l.c
index 402c6c4111..3901bd79da 100644
--- a/time/strftime_l.c
+++ b/time/strftime_l.c
@@ -267,15 +267,6 @@ static const CHAR_T zeroes[16] = /* "0000000000000000" */
# undef __mbsrtowcs_l
# define __mbsrtowcs_l(d, s, l, st, loc) __mbsrtowcs (d, s, l, st)
# endif
-# define widen(os, ws, l) \
- { \
- mbstate_t __st; \
- const char *__s = os; \
- memset (&__st, '\0', sizeof (__st)); \
- l = __mbsrtowcs_l (NULL, &__s, 0, &__st, loc); \
- ws = alloca ((l + 1) * sizeof (wchar_t)); \
- (void) __mbsrtowcs_l (ws, &__s, l, &__st, loc); \
- }
#endif
@@ -1342,11 +1333,31 @@ __strftime_internal (CHAR_T *s, size_t maxsize, const CHAR_T *format,
#ifdef COMPILE_WIDE
{
/* The zone string is always given in multibyte form. We have
- to transform it first. */
- wchar_t *wczone;
- size_t len;
- widen (zone, wczone, len);
- cpy (len, wczone);
+ to convert it to wide character. */
+ size_t w = pad == L_('-') || width < 0 ? 0 : width;
+ char const *z = zone;
+ mbstate_t st = {0};
+ size_t len = __mbsrtowcs_l (p, &z, maxsize - i, &st, loc);
+ if (len == (size_t) -1)
+ return 0;
+ size_t incr = len < w ? w : len;
+ if (incr >= maxsize - i)
+ {
+ errno = ERANGE;
+ return 0;
+ }
+ if (p)
+ {
+ if (len < w)
+ {
+ size_t delta = w - len;
+ __wmemmove (p + delta, p, len);
+ wchar_t wc = pad == L_('0') || pad == L_('+') ? L'0' : L' ';
+ wmemset (p, wc, delta);
+ }
+ p += incr;
+ }
+ i += incr;
}
#else
cpy (strlen (zone), zone);
--
2.23.0
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