[PATCH 05/11] i2c: ismt: Fix undefined behavior due to shift overflowing the constant

From: Borislav Petkov
Date: Tue Apr 05 2022 - 20:18:09 EST


From: Borislav Petkov <bp@xxxxxxx>

Fix:

drivers/i2c/busses/i2c-ismt.c: In function ‘ismt_hw_init’:
drivers/i2c/busses/i2c-ismt.c:770:2: error: case label does not reduce to an integer constant
case ISMT_SPGT_SPD_400K:
^~~~
drivers/i2c/busses/i2c-ismt.c:773:2: error: case label does not reduce to an integer constant
case ISMT_SPGT_SPD_1M:
^~~~

See https://lore.kernel.org/r/YkwQ6%2BtIH8GQpuct@xxxxxxx for the gory
details as to why it triggers with older gccs only.

Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Cc: Seth Heasley <seth.heasley@xxxxxxxxx>
Cc: Neil Horman <nhorman@xxxxxxxxxxxxx>
Cc: Wolfram Sang <wsa@xxxxxxxxxx>
Cc: linux-i2c@xxxxxxxxxxxxxxx
---
drivers/i2c/busses/i2c-ismt.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-ismt.c b/drivers/i2c/busses/i2c-ismt.c
index f4820fd3dc13..c0364314877e 100644
--- a/drivers/i2c/busses/i2c-ismt.c
+++ b/drivers/i2c/busses/i2c-ismt.c
@@ -145,8 +145,8 @@
#define ISMT_SPGT_SPD_MASK 0xc0000000 /* SMBus Speed mask */
#define ISMT_SPGT_SPD_80K 0x00 /* 80 kHz */
#define ISMT_SPGT_SPD_100K (0x1 << 30) /* 100 kHz */
-#define ISMT_SPGT_SPD_400K (0x2 << 30) /* 400 kHz */
-#define ISMT_SPGT_SPD_1M (0x3 << 30) /* 1 MHz */
+#define ISMT_SPGT_SPD_400K (0x2U << 30) /* 400 kHz */
+#define ISMT_SPGT_SPD_1M (0x3U << 30) /* 1 MHz */


/* MSI Control Register (MSICTL) bit definitions */
--
2.35.1