treewide: use get_random_u32_inclusive() when possible

These cases were done with this Coccinelle:

@@
expression H;
expression L;
@@
- (get_random_u32_below(H) + L)
+ get_random_u32_inclusive(L, H + L - 1)

@@
expression H;
expression L;
expression E;
@@
  get_random_u32_inclusive(L,
  H
- + E
- - E
  )

@@
expression H;
expression L;
expression E;
@@
  get_random_u32_inclusive(L,
  H
- - E
- + E
  )

@@
expression H;
expression L;
expression E;
expression F;
@@
  get_random_u32_inclusive(L,
  H
- - E
  + F
- + E
  )

@@
expression H;
expression L;
expression E;
expression F;
@@
  get_random_u32_inclusive(L,
  H
- + E
  + F
- - E
  )

And then subsequently cleaned up by hand, with several automatic cases
rejected if it didn't make sense contextually.

Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> # for infiniband
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

1 files changed, 2 insertions, 3 deletions

diff --git a/mm/swapfile.c b/mm/swapfile.c
index e9318305a24a..4ee31056d3f8 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -772,8 +772,7 @@ static void set_cluster_next(struct swap_info_struct *si, unsigned long next)
 		/* No free swap slots available */
 		if (si->highest_bit <= si->lowest_bit)
 			return;
-		next = si->lowest_bit +
-			get_random_u32_below(si->highest_bit - si->lowest_bit + 1);
+		next = get_random_u32_inclusive(si->lowest_bit, si->highest_bit);
 		next = ALIGN_DOWN(next, SWAP_ADDRESS_SPACE_PAGES);
 		next = max_t(unsigned int, next, si->lowest_bit);
 	}
@@ -3089,7 +3088,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 		 */
 		for_each_possible_cpu(cpu) {
 			per_cpu(*p->cluster_next_cpu, cpu) =
-				1 + get_random_u32_below(p->highest_bit);
+				get_random_u32_inclusive(1, p->highest_bit);
 		}
 		nr_cluster = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER);