From: Derrick Stolee <derrickstolee@xxxxxxxxxx>
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@xxxxxxxxxx>
---
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
