[PATCH AUTOSEL 4.4 19/21] x86/hw_breakpoints: Make default case in hw_breakpoint_arch_parse() return an error

[Sasha Levin]

From: Nathan Chancellor <natechancellor@xxxxxxxxx>

[ 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@xxxxxxxxxx>
Signed-off-by: Nathan Chancellor <natechancellor@xxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: clang-built-linux@xxxxxxxxxxxxxxxx
Link: https://github.com/ClangBuiltLinux/linux/issues/392
Link: https://lkml.kernel.org/r/20190307212756.4648-1-natechancellor@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 arch/x86/kernel/hw_breakpoint.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c
index 2bcfb5f2bc44..433f17d154e2 100644
--- a/arch/x86/kernel/hw_breakpoint.c
+++ b/arch/x86/kernel/hw_breakpoint.c
@@ -351,6 +351,7 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp)
 #endif
 	default:
 		WARN_ON_ONCE(1);
+		return -EINVAL;
 	}
 
 	/*
-- 
2.19.1