tree 7b35477567ebc46166ee327bf070e95e6b02f9cd
parent 1c0c275b11279a8305cf18a453e206d4891bbc48
author Tim Sell <Timothy.Sell@unisys.com> 1510939658 -0500
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1511875250 +0100

staging: unisys: visorbus: address theoretical int overflows

Add necessary casting to several places where we were doing 32-bit
arithmetic (unsigned) to produce a 64-bit (unsigned long) result, to
prevent the theoretical possibility of a 32-bit overflow during the
arithmetic.

FYI, these are unsigned long:

	ctx->param_bytes
	ctx->allocbytes

These are unsigned int:

	bytes
	phdr->name_offset
	phdr->name_length

Here is the test program demonstrating why we really need the casts:

void main()
{
	unsigned int i;
	unsigned long il;

	printf("sizeof(int) =%dn",sizeof(i));
	printf("sizeof(long)=%dn",sizeof(il));

	i = (unsigned int)((((unsigned long)(1)) << 32) - 1);
	printf("i                     = %un", i);
	il = i+1;
	printf("adding 1 withOUT cast = %lun", il);
	il = (unsigned long)i+1;
	printf("adding 1 WITH    cast = %lun", il);
}
[selltc@mac tmp]$ gcc x.c -o x.out
[selltc@mac tmp]$ ./x.out
sizeof(int) =4
sizeof(long)=8
i                     = 4294967295
adding 1 withOUT cast = 0
adding 1 WITH    cast = 4294967296

Signed-off-by: Tim Sell <Timothy.Sell@unisys.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David Kershner <david.kershner@unisys.com>
Reviewed-by: David Binder <david.binder@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>