[Drbd-dev] [patch] drbd: silence underflow warning in read_in_block()

[Drbd-dev] [patch] drbd: silence underflow warning in read_in_block()

[Dan Carpenter]

My static checker warns that "data_size" could be negative and underflow
the limit check.  The code looks suspicious but I don't know if it is a
real bug.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index b6c8aaf..15daf86d 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -1528,7 +1528,7 @@ read_in_block(struct drbd_peer_device *peer_device, u64 id, sector_t sector,
 	struct drbd_peer_request *peer_req;
 	struct page *page;
 	int dgs, ds, err;
-	int data_size = pi->size;
+	unsigned int data_size = pi->size;
 	void *dig_in = peer_device->connection->int_dig_in;
 	void *dig_vv = peer_device->connection->int_dig_vv;
 	unsigned long *data;

Re: [Drbd-dev] [patch] drbd: silence underflow warning in read_in_block()

[Lars Ellenberg]

On Tue, May 06, 2014 at 02:28:32PM +0300, Dan Carpenter wrote:
> My static checker warns that "data_size" could be negative and underflow
> the limit check.  The code looks suspicious but I don't know if it is a
> real bug.

"real life" bug only if you manage to receive corrupted data.
The maximum sent payload is DRBD_BIO_MAX_SIZE
which is an architecture independend constant (1U << 20).

Patch is correct, but while at it, we should revisit all "int data_size",
and make them all unsigned int...

	Lars

> 
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> 
> diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
> index b6c8aaf..15daf86d 100644
> --- a/drivers/block/drbd/drbd_receiver.c
> +++ b/drivers/block/drbd/drbd_receiver.c
> @@ -1528,7 +1528,7 @@ read_in_block(struct drbd_peer_device *peer_device, u64 id, sector_t sector,
>  	struct drbd_peer_request *peer_req;
>  	struct page *page;
>  	int dgs, ds, err;
> -	int data_size = pi->size;
> +	unsigned int data_size = pi->size;
>  	void *dig_in = peer_device->connection->int_dig_in;
>  	void *dig_vv = peer_device->connection->int_dig_vv;
>  	unsigned long *data;