[PATCH 5.0 93/95] i3c: Fix a shift wrap bug in i3c_bus_set_addr_slot_status()

Greg Kroah-Hartman
2019-05-09T18:58:00Z

From: Dan Carpenter <dan.carpenter@oracle.com>

commit 476c7e1d34f2a03b1aa5a924c50703053fe5f77c upstream.

The problem here is that addr can be I3C_BROADCAST_ADDR (126). That
means we're shifting by (126 * 2) % 64 which is 60. The
I3C_ADDR_SLOT_STATUS_MASK is an enum which is an unsigned int in GCC
so shifts greater than 31 are undefined.

Fixes: 3a379bbcea0a ("i3c: Add core I3C infrastructure")
Cc: <stable@vger.kernel.org>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/i3c/master.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/i3c/master.c
+++ b/drivers/i3c/master.c
@@ -385,8 +385,9 @@ static void i3c_bus_set_addr_slot_status
return;

ptr = bus->addrslots + (bitpos / BITS_PER_LONG);
- *ptr &= ~(I3C_ADDR_SLOT_STATUS_MASK << (bitpos % BITS_PER_LONG));
- *ptr |= status << (bitpos % BITS_PER_LONG);
+ *ptr &= ~((unsigned long)I3C_ADDR_SLOT_STATUS_MASK <<
+ (bitpos % BITS_PER_LONG));
+ *ptr |= (unsigned long)status << (bitpos % BITS_PER_LONG);
}

static bool i3c_bus_dev_addr_is_avail(struct i3c_bus *bus, u8 addr)