linux-kernel - [PATCH 5.1 28/30] i3c: Fix a shift wrap bug in i3c_bus_set_addr_slot

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Date:   Thu,  9 May 2019 20:43:00 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Dan Carpenter <dan.carpenter@...cle.com>,
        Boris Brezillon <boris.brezillon@...labora.com>
Subject: [PATCH 5.1 28/30] i3c: Fix a shift wrap bug in i3c_bus_set_addr_slot_status()

From: Dan Carpenter <dan.carpenter@...cle.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@...r.kernel.org>
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Boris Brezillon <boris.brezillon@...labora.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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)