From 9a205286bcca84b38d3ab1689f16236d1935af2d Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Wed, 5 Mar 2014 12:55:06 +0100 Subject: [PATCH] s390/compat: build error for large compat syscall args Enforce 32 bit types for all compat syscall argument types. This way we can make sure that all arguments get correct sign or zero extension. Otherwise incorrect code would be generated. E.g. for a 'long' type the COMPAT_SYSCALL_DEFINE macro wouldn't generate code that would cause sign extension of the passed in 32 bit user space parameter. This can cause quite subtle bugs like e.g. the one that was fixed with dfd948e32af2e "fs/compat: fix parameter handling for compat readv/writev syscalls". Signed-off-by: Heiko Carstens --- arch/s390/include/asm/compat.h | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/s390/include/asm/compat.h b/arch/s390/include/asm/compat.h index 5d7e8cf83bd6..d350ed9d0fbb 100644 --- a/arch/s390/include/asm/compat.h +++ b/arch/s390/include/asm/compat.h @@ -8,7 +8,11 @@ #include #define __TYPE_IS_PTR(t) (!__builtin_types_compatible_p(typeof(0?(t)0:0ULL), u64)) -#define __SC_DELOUSE(t,v) (t)(__TYPE_IS_PTR(t) ? ((v) & 0x7fffffff) : (v)) + +#define __SC_DELOUSE(t,v) ({ \ + BUILD_BUG_ON(sizeof(t) > 4 && !__TYPE_IS_PTR(t)); \ + (t)(__TYPE_IS_PTR(t) ? ((v) & 0x7fffffff) : (v)); \ +}) #define PSW32_MASK_PER 0x40000000UL #define PSW32_MASK_DAT 0x04000000UL