From: Szabolcs Nagy <szabolcs.nagy@arm.com>
To: <libc-alpha@sourceware.org>
Subject: [PATCH v2 1/4] Fix OOB read in stdlib thousand grouping parsing [BZ #29727]
Date: Fri, 28 Oct 2022 17:39:57 +0100 [thread overview]
Message-ID: <ca35ce47afa4a6cb3674f38413061db7635a73ec.1666974807.git.szabolcs.nagy@arm.com> (raw)
In-Reply-To: <cover.1666974807.git.szabolcs.nagy@arm.com>
__correctly_grouped_prefixmb only worked with thousands_len == 1,
otherwise it read past the end of cp or thousands.
This affects scanf formats like %'d, %'f and the internal but
exposed __strto{l,ul,f,d,..}_internal with grouping flag set
and an LC_NUMERIC locale where thousands_len > 1.
Avoid OOB access by considering thousands_len when initializing cp.
This fixes bug 29727.
Found by the morello port with strict bounds checking where
FAIL: stdlib/tst-strtod4
FAIL: stdlib/tst-strtod5i
crashed using a locale with thousands_len==3.
---
v2: - use const thousands_len for !USE_WIDE_CHAR.
---
stdlib/grouping.c | 16 +++++++---------
1 file changed, 7 insertions(+), 9 deletions(-)
diff --git a/stdlib/grouping.c b/stdlib/grouping.c
index be7922f5fd..06cbe7b9c7 100644
--- a/stdlib/grouping.c
+++ b/stdlib/grouping.c
@@ -52,21 +52,19 @@ __correctly_grouped_prefixmb (const STRING_TYPE *begin, const STRING_TYPE *end,
#endif
const char *grouping)
{
-#ifndef USE_WIDE_CHAR
- size_t thousands_len;
- int cnt;
-#endif
-
if (grouping == NULL)
return end;
-#ifndef USE_WIDE_CHAR
- thousands_len = strlen (thousands);
+#ifdef USE_WIDE_CHAR
+ size_t thousands_len = 1;
+#else
+ size_t thousands_len = strlen (thousands);
+ int cnt;
#endif
- while (end > begin)
+ while (end - begin >= thousands_len)
{
- const STRING_TYPE *cp = end - 1;
+ const STRING_TYPE *cp = end - thousands_len;
const char *gp = grouping;
/* Check first group. */
--
2.25.1
next prev parent reply other threads:[~2022-10-28 16:40 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-28 16:39 [PATCH v2 0/4] patches from the morello port Szabolcs Nagy
2022-10-28 16:39 ` Szabolcs Nagy [this message]
2022-11-02 15:20 ` [PATCH v2 1/4] Fix OOB read in stdlib thousand grouping parsing [BZ #29727] Andreas Schwab
2022-10-28 16:40 ` [PATCH v2 2/4] Fix off-by-one OOB write in iconv/tst-iconv-mt Szabolcs Nagy
2022-10-28 16:40 ` [PATCH v2 3/4] Fix elf/tst-dlmopen-twice not to exhaust static TLS Szabolcs Nagy
2022-10-28 17:04 ` Florian Weimer
2022-10-28 16:40 ` [PATCH v2 4/4] Remove unused scratch_buffer_dupfree Szabolcs Nagy
2022-10-28 17:06 ` Florian Weimer
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