On Tue, May 16, 2017 at 8:10 AM, Gao, Liming <[email protected]> wrote: > Sergey: > Could you give more detail on the undefined behavior on variadic parameters? > > I see https://bugzilla.tianocore.org/show_bug.cgi?id=410 describe this > issues found in the latest CLANG tool chain. Do you find other tool chain > reports it?
Yes, this is exactly the bug this patch fixes. As per the C99 standard: "The parameter parmN is the identifier of the rightmost parameter in the variable parameter list in the function definition (the one just before the , ...). If the parameter parmN is declared with the register storage class, with a function or array type, or with a type that is not compatible with the type that results after application of the default argument promotions, the behavior is undefined." That's exactly the case here since BOOLEAN is a typedef for unsigned char. It undergoes a promotion to an unsigned int which is not a compatible type for unsigned char. Correct me if I'm wrong. Regards, Sergey > > Thanks > Liming >> -----Original Message----- >> From: edk2-devel [mailto:[email protected]] On Behalf Of >> Sergey Temerkhanov >> Sent: Tuesday, May 16, 2017 10:57 AM >> To: [email protected] >> Subject: [edk2] [PATCH] MdePkg: Fix undefined behavior on variadic parameters >> >> Fix undefined behavior by avoiding parameter type promotion >> >> Signed-off-by: Sergey Temerkhanov <[email protected]> >> --- >> MdePkg/Include/Library/UefiLib.h | 2 +- >> MdePkg/Library/UefiLib/UefiLib.c | 2 +- >> 2 files changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/MdePkg/Include/Library/UefiLib.h >> b/MdePkg/Include/Library/UefiLib.h >> index 0b14792..4e4697c 100644 >> --- a/MdePkg/Include/Library/UefiLib.h >> +++ b/MdePkg/Include/Library/UefiLib.h >> @@ -818,7 +818,7 @@ CHAR8 * >> EFIAPI >> GetBestLanguage ( >> IN CONST CHAR8 *SupportedLanguages, >> - IN BOOLEAN Iso639Language, >> + IN UINTN Iso639Language, >> ... >> ); >> >> diff --git a/MdePkg/Library/UefiLib/UefiLib.c >> b/MdePkg/Library/UefiLib/UefiLib.c >> index a7eee01..74528ec 100644 >> --- a/MdePkg/Library/UefiLib/UefiLib.c >> +++ b/MdePkg/Library/UefiLib/UefiLib.c >> @@ -1514,7 +1514,7 @@ CHAR8 * >> EFIAPI >> GetBestLanguage ( >> IN CONST CHAR8 *SupportedLanguages, >> - IN BOOLEAN Iso639Language, >> + IN UINTN Iso639Language, >> ... >> ) >> { >> -- >> 2.7.4 >> >> _______________________________________________ >> edk2-devel mailing list >> [email protected] >> https://lists.01.org/mailman/listinfo/edk2-devel _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
