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i3c: Fix a shift wrap bug in i3c_bus_set_addr_slot_status()

PATCH New Dan Carpenter 1 participant 1 message Apr 23, 2019

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Dan Carpenter

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PATCH 1/1 i3c: Fix a shift wrap bug in i3c_bus_set_addr_slot_status()

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")
Signed-off-by Dan Carpenter <[email protected]>

---
This patch is from static analysis. I really know what *ptr is used for and I haven't tested the code. The other question is would be testing this code on 32 bit systems. Please review carefully.

 drivers/i3c/master.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
drivers/i3c/master.c +3 -2
index 1412abcff010..5f4bd52121fe 100644
@@ -385,8 +385,9 @@ static void i3c_bus_set_addr_slot_status(struct i3c_bus *bus, u16 addr,
 		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)
Signature · 1 line
2.18.0