[PATCH v3 03/15] NTB: Fix UB/bug in ntb_mw_get_align()

Serge Semin
2017-12-05T22:44:07Z

Simple (1 << pidx) operation causes undefined behaviour when
pidx >= 32. It must be casted to u64 to match the actual return
value of ntb_link_is_up() method, so to have all the possible
peer indexes covered and to get rid of undefined behaviour.
Additionally there are special macros in "linux/bitops.h" to perform
the bit-set-shift operations, so it's recommended to have them used
for proper bit setting.

Signed-off-by: Serge Semin <fancer.lancer@gmail.com>
---
include/linux/ntb.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/ntb.h b/include/linux/ntb.h
index c1646f2c6344..488e586fb76c 100644
--- a/include/linux/ntb.h
+++ b/include/linux/ntb.h
@@ -764,7 +764,7 @@ static inline int ntb_mw_get_align(struct ntb_dev *ntb, int pidx, int widx,
resource_size_t *size_align,
resource_size_t *size_max)
{
- if (!(ntb_link_is_up(ntb, NULL, NULL) & (1 << pidx)))
+ if (!(ntb_link_is_up(ntb, NULL, NULL) & BIT_ULL(pidx)))
return -ENOTCONN;

return ntb->ops->mw_get_align(ntb, pidx, widx, addr_align, size_align,
--
2.12.0