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3ab5b78c47Currently, 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 *). Since the existence of the bug doesn't always prevent a Gentoo Prefix bootstrapping, it can lurk inside the system and remain undetected, furthermore, it's technically a C programming bug, other platforms could've been affected as well in theory. Thus, we also bump the package version. Closes: https://bugs.gentoo.org/871324 Signed-off-by: Yifeng Li <tomli@tomli.me> Signed-off-by: Sam James <sam@gentoo.org>
48 lines
1.6 KiB
Diff
48 lines
1.6 KiB
Diff
https://github.com/westes/flex/issues/539
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https://github.com/westes/flex/pull/554
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https://bugs.gentoo.org/871324
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This is a backported version for applying to v2.6.4
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instead of git.
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From cce2df853386d5b5b60445b1204dcca08e9f259e Mon Sep 17 00:00:00 2001
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From: Yifeng Li <tomli@tomli.me>
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Date: Mon, 20 Feb 2023 11:23:52 +0000
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Subject: [PATCH] Fix #539 crash on Apple M1 by casting 0 to (char *)
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explicitly
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Currently, when the NULL-terminated variadic function
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filter_create_ext() is invoked, the value "0" is passed as
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the last argument to act as a terminator. However, this is
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an integer value, which is incompatible with the pointer
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data type expected by filter_create_ext().
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This is undefined behavior in C, correct operation is not
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guaranteed. In fact, it causes flex to crash on Apple M1
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when GCC is used - the loop is not terminated when it should,
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instead, it keeps running, corrupting the argument list for
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invoking m4. As a result, it creates the following error:
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> flex: fatal internal error, exec of gm4 failed
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This commit fixes the problem by explicitly casting the value 0 to
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the correct pointer type (char *).
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Signed-off-by: Yifeng Li <tomli@tomli.me>
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---
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src/main.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/src/main.c b/src/main.c
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index e5eac44fe..5c9086183 100644
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--- a/src/main.c
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+++ b/src/main.c
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@@ -380,7 +380,7 @@ void check_options (void)
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}
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}
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}
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- filter_create_ext(output_chain, m4, "-P", 0);
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+ filter_create_ext(output_chain, m4, "-P", (char *) 0);
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filter_create_int(output_chain, filter_fix_linedirs, NULL);
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/* For debugging, only run the requested number of filters. */
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