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Date:   Fri, 17 Apr 2020 14:26:24 +0300
From:   Dan Carpenter <dan.carpenter@oracle.com>
To:     Jason Gunthorpe <jgg@ziepe.ca>
Cc:     Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
        selvin.xavier@broadcom.com, devesh.sharma@broadcom.com,
        dledford@redhat.com, leon@kernel.org, colin.king@canonical.com,
        roland@purestorage.com, linux-rdma@vger.kernel.org,
        linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: Re: [PATCH] RDMA/ocrdma: Fix an off-by-one issue in 'ocrdma_add_stat'
Message-ID: <20200417112624.GS1163@kadam>
References: <20200328073040.24429-1-christophe.jaillet@wanadoo.fr>
 <20200414183441.GA28870@ziepe.ca>
 <20200416130847.GP1163@kadam>
 <20200416184754.GZ5100@ziepe.ca>
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On Thu, Apr 16, 2020 at 03:47:54PM -0300, Jason Gunthorpe wrote:
> On Thu, Apr 16, 2020 at 04:08:47PM +0300, Dan Carpenter wrote:
> > On Tue, Apr 14, 2020 at 03:34:41PM -0300, Jason Gunthorpe wrote:
> > > The memcpy is still kind of silly right? What about this:
> > > 
> > > static int ocrdma_add_stat(char *start, char *pcur, char *name, u64 count)
> > > {
> > > 	size_t len = (start + OCRDMA_MAX_DBGFS_MEM) - pcur;
> > > 	int cpy_len;
> > > 
> > > 	cpy_len = snprintf(pcur, len, "%s: %llu\n", name, count);
> > > 	if (cpy_len >= len || cpy_len < 0) {
> > 
> > The kernel version of snprintf() doesn't and will never return
> > negatives.  It would cause a huge security headache if it started
> > returning negatives.
> 
> Begs the question why it returns an int then :)

People should use "int" as their default type.  "int i;".  It means
"This is a normal number.  Nothing special about it.  It's not too high.
It's not defined by hardware requirements."  Other types call attention
to themselves, but int is the humble datatype.

regards,
dan carpenter