mirror of https://github.com/acidanthera/audk.git
da117dda23
In function UfsBlockIoPeimGetMediaInfo(), the following expression: Private->Media[DeviceIndex].LastBlock = (Capacity16.LastLba3 << 24) | (Capacity16.LastLba2 << 16) | (Capacity16.LastLba1 << 8) | Capacity16.LastLba0; (There is also a similar case in this function.) will involve undefined behavior in signed left shift operations. Since Capacity16.LastLbaX is of type UINT8, and Private->Media[DeviceIndex].LastBlock is of type UINT64. Therefore, Capacity16.LastLbaX will be promoted to int (32 bits, signed) first, and then perform the left shift operation. 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. So if bit 7 of Capacity16.LastLba3 is 1, (Capacity16.LastLba3 << 24) will be out of the range within int type. The undefined behavior of the signed left shift will lead to a potential of setting the high 32 bits of Private->Media[DeviceIndex].LastBlock to 1 during the cast from type int to type UINT64. This commit will add an explicit UINT32 type cast for Capacity16.LastLba3 to resolve this issue. Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Hao Wu <hao.a.wu@intel.com> Reviewed-by: Feng Tian <feng.tian@intel.com> |
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| .. | ||
| Application | ||
| Bus | ||
| Core | ||
| Include | ||
| Library | ||
| Logo | ||
| Universal | ||
| Contributions.txt | ||
| License.txt | ||
| MdeModulePkg.dec | ||
| MdeModulePkg.dsc | ||
| MdeModulePkg.uni | ||
| MdeModulePkgExtra.uni | ||