[PATCH 4.9 144/240] liquidio: Fix unintented sign extension of a left shift of a u16

Greg Kroah-Hartman
2021-05-20T11:17:09Z

From: Colin Ian King <colin.king@canonical.com>

[ Upstream commit 298b58f00c0f86868ea717426beb5c1198772f81 ]

The macro CN23XX_PEM_BAR1_INDEX_REG is being used to shift oct->pcie_port
(a u16) left 24 places. There are two subtle issues here, first the
shift gets promoted to an signed int and then sign extended to a u64.
If oct->pcie_port is 0x80 or more then the upper bits get sign extended
to 1. Secondly shfiting a u16 24 bits will lead to an overflow so it
needs to be cast to a u64 for all the bits to not overflow.

It is entirely possible that the u16 port value is never large enough
for this to fail, but it is useful to fix unintended overflows such
as this.

Fix this by casting the port parameter to the macro to a u64 before
the shift.

Addresses-Coverity: ("Unintended sign extension")
Fixes: 5bc67f587ba7 ("liquidio: CN23XX register definitions")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/cavium/liquidio/cn23xx_pf_regs.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/cavium/liquidio/cn23xx_pf_regs.h b/drivers/net/ethernet/cavium/liquidio/cn23xx_pf_regs.h
index 03d79d95ab75..d7e0d2ce15c1 100644
--- a/drivers/net/ethernet/cavium/liquidio/cn23xx_pf_regs.h
+++ b/drivers/net/ethernet/cavium/liquidio/cn23xx_pf_regs.h
@@ -526,7 +526,7 @@
#define CN23XX_BAR1_INDEX_OFFSET 3

#define CN23XX_PEM_BAR1_INDEX_REG(port, idx) \
- (CN23XX_PEM_BAR1_INDEX_START + ((port) << CN23XX_PEM_OFFSET) + \
+ (CN23XX_PEM_BAR1_INDEX_START + (((u64)port) << CN23XX_PEM_OFFSET) + \
((idx) << CN23XX_BAR1_INDEX_OFFSET))

/*############################ DPI #########################*/
--
2.30.2