From: "Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com>
To: git@vger.kernel.org
Cc: gitster@pobox.com, Derrick Stolee <derrickstolee@github.com>,
Derrick Stolee <derrickstolee@github.com>
Subject: [PATCH] compat/win32: correct for incorrect compiler warning
Date: Tue, 19 Jul 2022 18:45:54 +0000 [thread overview]
Message-ID: <pull.1294.git.1658256354725.gitgitgadget@gmail.com> (raw)
From: Derrick Stolee <derrickstolee@github.com>
The 'win build' job of our CI build is failing with the following error:
compat/win32/syslog.c: In function 'syslog':
compat/win32/syslog.c:53:17: error: pointer 'pos' may be used after \
'realloc' [-Werror=use-after-free]
53 | memmove(pos + 2, pos + 1, strlen(pos));
CC compat/poll/poll.o
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
compat/win32/syslog.c:47:23: note: call to 'realloc' here
47 | str = realloc(str, st_add(++str_len, 1));
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
However, between this realloc() and the use we have a line that resets
the value of 'pos'. Thus, this error is incorrect. It is likely due to a
new version of the compiler on the CI machines.
Instead of waiting for a new compiler, create a new variable to avoid
this error.
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
---
Fix error in response to compiler bug
See [1] for an example of this error in the wild.
[1]
https://github.com/gitgitgadget/git/runs/7413762368?check_suite_focus=true#step:4:297
Thanks, -Stolee
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1294%2Fderrickstolee%2Frealloc-error-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1294/derrickstolee/realloc-error-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/1294
compat/win32/syslog.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/compat/win32/syslog.c b/compat/win32/syslog.c
index 1f8d8934cc9..0af18d88825 100644
--- a/compat/win32/syslog.c
+++ b/compat/win32/syslog.c
@@ -44,6 +44,7 @@ void syslog(int priority, const char *fmt, ...)
while ((pos = strstr(str, "%1")) != NULL) {
size_t offset = pos - str;
+ char *new_pos;
char *oldstr = str;
str = realloc(str, st_add(++str_len, 1));
if (!str) {
@@ -51,9 +52,9 @@ void syslog(int priority, const char *fmt, ...)
warning_errno("realloc failed");
return;
}
- pos = str + offset;
- memmove(pos + 2, pos + 1, strlen(pos));
- pos[1] = ' ';
+ new_pos = str + offset;
+ memmove(new_pos + 2, new_pos + 1, strlen(new_pos));
+ new_pos[1] = ' ';
}
switch (priority) {
base-commit: 71a8fab31b70c417e8f5b5f716581f89955a7082
--
gitgitgadget
next reply other threads:[~2022-07-19 18:46 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-19 18:45 Derrick Stolee via GitGitGadget [this message]
2022-07-19 19:48 ` [PATCH] compat/win32: correct for incorrect compiler warning Eric Sunshine
2022-07-19 20:01 ` Derrick Stolee
2022-07-19 20:13 ` Junio C Hamano
2022-07-21 14:17 ` Phillip Wood
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