x86/hw_breakpoints: Make default case in hw_breakpoint_arch_parse() return an error

[ Upstream commit e898e69d6b9475bf123f99b3c5d1a67bb7cb2361 ]

When building with -Wsometimes-uninitialized, Clang warns:

arch/x86/kernel/hw_breakpoint.c:355:2: warning: variable 'align' is used
uninitialized whenever switch default is taken
[-Wsometimes-uninitialized]

The default cannot be reached because arch_build_bp_info() initializes
hw->len to one of the specified cases. Nevertheless the warning is valid
and returning -EINVAL makes sure that this cannot be broken by future
modifications.

Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: clang-built-linux@googlegroups.com
Link: https://github.com/ClangBuiltLinux/linux/issues/392
Link: https://lkml.kernel.org/r/20190307212756.4648-1-natechancellor@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c
index 8771766d46b6c3e74d914136578f0b8d6f64b5ad..9954a604a8227f53a26e118fa0bcf338b485e5b1 100644 (file)
--- a/arch/x86/kernel/hw_breakpoint.c
+++ b/arch/x86/kernel/hw_breakpoint.c
@@ -352,6 +352,7 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp)
 #endif
        default:
                WARN_ON_ONCE(1);
+               return -EINVAL;
        }
 
        /*