ima/evm: Fix type mismatch

The endianness of a variable written to the measurement list cannot be
determined at compile time, as it depends on the value of the
ima_canonical_fmt global variable (set through a kernel option with the
same name if the machine is big endian).

If ima_canonical_fmt is false, the endianness of a variable is the same as
the machine; if ima_canonical_fmt is true, the endianness is little endian.
The warning arises due to this type of instruction:

var = cpu_to_leXX(var)

which tries to assign a value in little endian to a variable with native
endianness (little or big endian).

Given that the variables set with this instruction are not used in any
operation but just written to a buffer, it is safe to force the type of the
value being set to be the same of the type of the variable with:

var = (__force <var type>)cpu_to_leXX(var)

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

security/integrity/evm/evm_main.c

@@ -360,7 +360,7 @@ int evm_read_protected_xattrs(struct dentry *dentry, u8 *buffer,
 			size = sizeof(u32);
 			if (buffer) {
 				if (canonical_fmt)
-					rc = cpu_to_le32(rc);
+					rc = (__force int)cpu_to_le32(rc);
 
 				*(u32 *)(buffer + total_size) = rc;
 			}