genwqe: Prevent an integer overflow in the ioctl

There are a couple potential integer overflows here.

	round_up(m->size + (m->addr & ~PAGE_MASK), PAGE_SIZE);

The first thing is that the "m->size + (...)" addition could overflow,
and the second is that round_up() overflows to zero if the result is
within PAGE_SIZE of the type max.

In this code, the "m->size" variable is an u64 but we're saving the
result in "map_size" which is an unsigned long and genwqe_user_vmap()
takes an unsigned long as well.  So I have used ULONG_MAX as the upper
bound.  From a practical perspective unsigned long is fine/better than
trying to change all the types to u64.

Fixes: eaf4722d4645 ("GenWQE Character device and DDCB queue")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/misc/genwqe/card_dev.c b/drivers/misc/genwqe/card_dev.c
index 8c1b63a..d2098b4 100644 (file)
--- a/drivers/misc/genwqe/card_dev.c
+++ b/drivers/misc/genwqe/card_dev.c
@@ -780,6 +780,8 @@ static int genwqe_pin_mem(struct genwqe_file *cfile, struct genwqe_mem *m)
 
        if ((m->addr == 0x0) || (m->size == 0))
                return -EINVAL;
+       if (m->size > ULONG_MAX - PAGE_SIZE - (m->addr & ~PAGE_MASK))
+               return -EINVAL;
 
        map_addr = (m->addr & PAGE_MASK);
        map_size = round_up(m->size + (m->addr & ~PAGE_MASK), PAGE_SIZE);

diff --git a/drivers/misc/genwqe/card_utils.c b/drivers/misc/genwqe/card_utils.c
index 89cff9d..7571700 100644 (file)
--- a/drivers/misc/genwqe/card_utils.c
+++ b/drivers/misc/genwqe/card_utils.c
@@ -586,6 +586,10 @@ int genwqe_user_vmap(struct genwqe_dev *cd, struct dma_mapping *m, void *uaddr,
        /* determine space needed for page_list. */
        data = (unsigned long)uaddr;
        offs = offset_in_page(data);
+       if (size > ULONG_MAX - PAGE_SIZE - offs) {
+               m->size = 0;    /* mark unused and not added */
+               return -EINVAL;
+       }
        m->nr_pages = DIV_ROUND_UP(offs + size, PAGE_SIZE);
 
        m->page_list = kcalloc(m->nr_pages,