Hao: I sent another patch to introduce CacluateCrc32() API in BaseLib. It will update MdeModulePkg Crc32 to depend on BaseLib. And, BaseLib CacluateCrc32() has no such logic. So, I think this patch is not necessary.
Thanks Liming >-----Original Message----- >From: edk2-devel [mailto:[email protected]] On Behalf Of Hao >Wu >Sent: Thursday, September 21, 2017 2:46 PM >To: [email protected] >Cc: Wu, Hao A <[email protected]>; Paolo Bonzini <[email protected]>; >Dong, Eric <[email protected]>; Zeng, Star <[email protected]> >Subject: [edk2] [PATCH v2 5/6] MdeModulePkg/Crc32: Fix possible out of >range left shift > >REF: https://bugzilla.tianocore.org/show_bug.cgi?id=697 > >Within function ReverseBits(), left shift operations of 1 in the >following statements: >"(1 << Index)" and "(1 << (31 - Index))" > >will incur possible out of range left shift when Index is either 0 or >31, since "1 << 31" is possible to exceed the range of type 'int' >(signed). > >According to the C11 spec, Section 6.5.7: >> 4 The result of E1 << E2 is E1 left-shifted E2 bit positions; vacated >> bits are filled with zeros. If E1 has an unsigned type, the value >> of the result is E1 * 2^E2 , reduced modulo one more than the >> maximum value representable in the result type. If E1 has a signed >> type and nonnegative value, and E1 * 2^E2 is representable in the >> result type, then that is the resulting value; otherwise, the >> behavior is undefined. > >This commit uses '1U' instead of '1' to resolve this issue. > >Cc: Steven Shi <[email protected]> >Cc: Star Zeng <[email protected]> >Cc: Eric Dong <[email protected]> >Cc: Paolo Bonzini <[email protected]> >Contributed-under: TianoCore Contribution Agreement 1.1 >Signed-off-by: Hao Wu <[email protected]> >--- > MdeModulePkg/Core/RuntimeDxe/Crc32.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > >diff --git a/MdeModulePkg/Core/RuntimeDxe/Crc32.c >b/MdeModulePkg/Core/RuntimeDxe/Crc32.c >index a6fe77fa34..2cd234b562 100644 >--- a/MdeModulePkg/Core/RuntimeDxe/Crc32.c >+++ b/MdeModulePkg/Core/RuntimeDxe/Crc32.c >@@ -7,7 +7,7 @@ > EFI Runtime Services Table are converted from physical address to > virtual addresses. This requires that the 32-bit CRC be recomputed. > >-Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR> >+Copyright (c) 2006 - 2017, Intel Corporation. All rights reserved.<BR> > This program and the accompanying materials > are licensed and made available under the terms and conditions of the BSD >License > which accompanies this distribution. The full text of the license may be > found >at >@@ -79,8 +79,8 @@ ReverseBits ( > > NewValue = 0; > for (Index = 0; Index < 32; Index++) { >- if ((Value & (1 << Index)) != 0) { >- NewValue = NewValue | (1 << (31 - Index)); >+ if ((Value & (1U << Index)) != 0) { >+ NewValue = NewValue | (1U << (31 - Index)); > } > } > >-- >2.12.0.windows.1 > >_______________________________________________ >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
