Commit 2e3883d0 authored by Peter Maydell's avatar Peter Maydell
Browse files

disas/m68k: Avoid unintended sign extension in get_field() 



In get_field(), we take an 'unsigned char' value and shift it left,
which implicitly promotes it to 'signed int', before ORing it into an
'unsigned long' type.  If 'unsigned long' is 64 bits then this will
result in a sign extension and the top 32 bits of the result will be
1s.  Add explicit casts to unsigned long before shifting to prevent
this.

(Spotted by Coverity, CID 715697.)

Signed-off-by: default avatarPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: default avatarLaurent Vivier <laurent@vivier.eu>
Message-id: 1488556233-31246-4-git-send-email-peter.maydell@linaro.org
parent 3f168b5d

disas/m68k.c

+3 −2
Original line number Diff line number Diff line
@@ -4685,10 +4685,11 @@ get_field (const unsigned char *data, enum floatformat_byteorders order, 
	/* This is the last byte; zero out the bits which are not part of

	   this field.  */

	result |=

	  (*(data + cur_byte) & ((1 << (len - cur_bitshift)) - 1))

	  (unsigned long)(*(data + cur_byte)

			  & ((1 << (len - cur_bitshift)) - 1))

	    << cur_bitshift;

      else

	result |= *(data + cur_byte) << cur_bitshift;

	result |= (unsigned long)*(data + cur_byte) << cur_bitshift;

      cur_bitshift += FLOATFORMAT_CHAR_BIT;

      if (order == floatformat_little)

	++cur_byte;