From: "Carlo Marcelo Arenas Belón" <carenas@gmail.com>
To: git@vger.kernel.org
Cc: davvid@gmail.com, gitster@pobox.com
Subject: [PATCH] wrapper: avoid UB in macOS
Date: Sun, 16 Jun 2019 11:40:03 -0700 [thread overview]
Message-ID: <20190616184003.17236-1-carenas@gmail.com> (raw)
0620b39b3b ("compat: add a mkstemps() compatibility function", 2009-05-31)
included a function based on code from libiberty which would result in
undefined behaviour in platforms where timeval's tv_usec is a 32-bit signed
type as shown by:
wrapper.c:505:31: runtime error: left shift of 594546 by 16 places cannot be represented in type '__darwin_suseconds_t' (aka 'int')
interestingly the version of this code from gcc never had this bug and the
code had a cast that would had prevented the issue (at least in 64-bit
platforms) but was misapplied.
change the cast to uint64_t so it also works in 32-bit platforms.
Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
---
wrapper.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/wrapper.c b/wrapper.c
index ea3cf64d4c..1e45ab7b92 100644
--- a/wrapper.c
+++ b/wrapper.c
@@ -502,7 +502,7 @@ int git_mkstemps_mode(char *pattern, int suffix_len, int mode)
* Try TMP_MAX different filenames.
*/
gettimeofday(&tv, NULL);
- value = ((size_t)(tv.tv_usec << 16)) ^ tv.tv_sec ^ getpid();
+ value = ((uint64_t)tv.tv_usec << 16) ^ tv.tv_sec ^ getpid();
filename_template = &pattern[len - 6 - suffix_len];
for (count = 0; count < TMP_MAX; ++count) {
uint64_t v = value;
--
2.22.0
next reply other threads:[~2019-06-16 18:40 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-16 18:40 Carlo Marcelo Arenas Belón [this message]
2019-06-19 14:40 ` [PATCH] wrapper: avoid UB in macOS Junio C Hamano
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