From d8a09b3a041c8983ce51106ae7f92a11142f8470 Mon Sep 17 00:00:00 2001 From: Ryan Libby Date: Tue, 15 Dec 2020 09:20:48 -0800 Subject: [PATCH] lua: avoid gcc -Wreturn-local-addr bug Avoid a bug with gcc's -Wreturn-local-addr warning with some obfuscation. In buggy versions of gcc, if a return value is an expression that involves the address of a local variable, and even if that address is legally converted to a non-pointer type, a warning may be emitted and the value of the address may be replaced with zero. Howerver, buggy versions don't emit the warning or replace the value when simply returning a local variable of non-pointer type. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90737 Reviewed-by: Brian Behlendorf Signed-off-by: Ryan Libby Closes #11337 --- module/lua/ldo.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/module/lua/ldo.c b/module/lua/ldo.c index 0344a29fd..474fe659b 100644 --- a/module/lua/ldo.c +++ b/module/lua/ldo.c @@ -33,14 +33,16 @@ #if defined (_KERNEL) && defined(__linux__) #include static intptr_t stack_remaining(void) { - char local; - return (intptr_t)(&local - (char *)current->stack); + intptr_t local; + local = (intptr_t)&local - (intptr_t)current->stack; + return local; } #elif defined (_KERNEL) && defined(__FreeBSD__) #include static intptr_t stack_remaining(void) { - char local; - return (intptr_t)(&local - (char *)curthread->td_kstack); + intptr_t local; + local = (intptr_t)&local - (intptr_t)curthread->td_kstack; + return local; } #else static intptr_t stack_remaining(void) {