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SubjectRe: [PATCH] x86/umip: Fix insn_get_code_seg_params()'s return value
On Thu, Nov 23, 2017 at 10:19:51AM +0100, Borislav Petkov wrote:
> From: Borislav Petkov <bp@suse.de>
>
> In order to save on redundant structs definitions
> insn_get_code_seg_params() was made to return two 4-bit values in a char
> but clang complains:
>
> arch/x86/lib/insn-eval.c:780:10: warning: implicit conversion from 'int' to 'char'
> changes value from 132 to -124 [-Wconstant-conversion]
> return INSN_CODE_SEG_PARAMS(4, 8);
> ~~~~~~ ^~~~~~~~~~~~~~~~~~~~~~~~~~
> ./arch/x86/include/asm/insn-eval.h:16:57: note: expanded from macro 'INSN_CODE_SEG_PARAMS'
> #define INSN_CODE_SEG_PARAMS(oper_sz, addr_sz) (oper_sz | (addr_sz << 4))
>
> Those two values do get picked apart afterwards the opposite way of how
> they were ORed so wrt to the LSByte, the return value is the same.
>
> But this function returns -EINVAL in the error case, which is an int. So
> make it return an int which is the native word size anyway and thus fix
> the clang warning.
>
> Signed-off-by: Borislav Petkov <bp@suse.de>
> Reported-by: Kees Cook <keescook@google.com>
> Reported-by: Nick Desaulniers <nick.desaulniers@gmail.com>
> Cc: ricardo.neri-calderon@linux.intel.com

Thanks Kees and Nick for finding this bug. Thanks Borislav for the quick fix!
This change looks OK to me.

BR,
Ricardo

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