On Wed, May 17, 2017 at 6:30 PM, Gao, Liming <[email protected]> wrote: > Sergey: > Now, VS and GCC don't report such issue. How do you find them?
Clang build for ARM64 revealed it. > And, this change modifies the function API, does it impact the consumer code? No changes to the consumer code are needed - integer promotions are handled by the compilers. In fact, even the ABI remains the same b/c full words are passed as function parameters. Regards, Sergey > > Thanks > Liming >> -----Original Message----- >> From: Sergei Temerkhanov [mailto:[email protected]] >> Sent: Tuesday, May 16, 2017 8:11 PM >> To: Gao, Liming <[email protected]> >> Cc: [email protected] >> Subject: Re: [edk2] [PATCH] MdePkg: Fix undefined behavior on variadic >> parameters >> >> 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
