From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48180) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fGld9-0000va-0J for qemu-devel@nongnu.org; Thu, 10 May 2018 09:29:11 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fGld8-0004SB-0y for qemu-devel@nongnu.org; Thu, 10 May 2018 09:29:10 -0400 References: <20180508212718.1482663-1-eblake@redhat.com> From: Paolo Bonzini Message-ID: Date: Thu, 10 May 2018 15:28:58 +0200 MIME-Version: 1.0 In-Reply-To: <20180508212718.1482663-1-eblake@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] iscsi: Avoid potential for get_status overflow List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Blake , qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, Ronnie Sahlberg , Peter Lieven , Kevin Wolf , Max Reitz , "open list:iSCSI" On 08/05/2018 23:27, Eric Blake wrote: > Detected by Coverity: Multiplying two 32-bit int and assigning > the result to a 64-bit number is a risk of overflow. Prior to > the conversion to byte-based interfaces, the block layer took > care of ensuring that a status request never exceeded 2G in > the driver; but after that conversion, the block layer expects > drivers to deal with any size request (the driver can always > truncate the request size back down, as long as it makes > progress). So, in the off-chance that someone makes a large > request, we are at the mercy of whether iscsi_get_lba_status_task() > will cap things to at most INT_MAX / iscsilun->block_size when > it populates lbasd->num_blocks; since I could not easily audit > that, it's better to be safe than sorry by just forcing a 64-bit > multiply. > > Fixes: 92809c36 > CC: qemu-stable@nongnu.org > Signed-off-by: Eric Blake > --- > block/iscsi.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/block/iscsi.c b/block/iscsi.c > index 35423ded03b..a6311b9a320 100644 > --- a/block/iscsi.c > +++ b/block/iscsi.c > @@ -732,7 +732,7 @@ retry: > goto out_unlock; > } > > - *pnum = lbasd->num_blocks * iscsilun->block_size; > + *pnum = (int64_t) lbasd->num_blocks * iscsilun->block_size; > > if (lbasd->provisioning == SCSI_PROVISIONING_TYPE_DEALLOCATED || > lbasd->provisioning == SCSI_PROVISIONING_TYPE_ANCHORED) { > Queued, thanks. Paolo