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https://github.com/westes/flex/issues/539
https://github.com/westes/flex/pull/554
https://bugs.gentoo.org/871324
This is a backported version for applying to v2.6.4
instead of git.
From cce2df853386d5b5b60445b1204dcca08e9f259e Mon Sep 17 00:00:00 2001
From: Yifeng Li <tomli@tomli.me>
Date: Mon, 20 Feb 2023 11:23:52 +0000
Subject: [PATCH] Fix #539 crash on Apple M1 by casting 0 to (char *)
explicitly
Currently, when the NULL-terminated variadic function
filter_create_ext() is invoked, the value "0" is passed as
the last argument to act as a terminator. However, this is
an integer value, which is incompatible with the pointer
data type expected by filter_create_ext().
This is undefined behavior in C, correct operation is not
guaranteed. In fact, it causes flex to crash on Apple M1
when GCC is used - the loop is not terminated when it should,
instead, it keeps running, corrupting the argument list for
invoking m4. As a result, it creates the following error:
> flex: fatal internal error, exec of gm4 failed
This commit fixes the problem by explicitly casting the value 0 to
the correct pointer type (char *).
Signed-off-by: Yifeng Li <tomli@tomli.me>
---
src/main.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/main.c b/src/main.c
index e5eac44fe..5c9086183 100644
--- a/src/main.c
+++ b/src/main.c
@@ -380,7 +380,7 @@ void check_options (void)
}
}
}
- filter_create_ext(output_chain, m4, "-P", 0);
+ filter_create_ext(output_chain, m4, "-P", (char *) 0);
filter_create_int(output_chain, filter_fix_linedirs, NULL);
/* For debugging, only run the requested number of filters. */
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