linux-kernel - Re: [PATCH] mtd: stm32-quadspi: replace "%p" with "%pK"

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Date:   Fri, 6 Jul 2018 16:47:32 +0200
From:   Boris Brezillon <boris.brezillon@...tlin.com>
To:     Richard Weinberger <richard@....at>
Cc:     Benjamin Gaignard <benjamin.gaignard@...aro.org>,
        marek.vasut@...il.com, dwmw2@...radead.org,
        computersforpeace@...il.com, mcoquelin.stm32@...il.com,
        alexandre.torgue@...com, linux-mtd@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Benjamin Gaignard <benjamin.gaignard@...com>
Subject: Re: [PATCH] mtd: stm32-quadspi: replace "%p" with "%pK"

On Fri, 06 Jul 2018 16:44:44 +0200
Richard Weinberger <richard@....at> wrote:

> Am Freitag, 6. Juli 2018, 15:05:25 CEST schrieb Benjamin Gaignard:
> > The format specifier "%p" can leak kernel addresses.
> > Use "%pK" instead.  
> 
> Does %pK really make sense for dev_dbg()?
> When the driver is being debugged "leaking" is on purpose. :)

%p already gives you a hash of the pointer address. At least with %pK
you can turn it off through a sysctl :).

> 
> Thanks,
> //richard
>  
> > Signed-off-by: Benjamin Gaignard <benjamin.gaignard@...com>
> > ---
> >  drivers/mtd/spi-nor/stm32-quadspi.c | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/mtd/spi-nor/stm32-quadspi.c b/drivers/mtd/spi-nor/stm32-quadspi.c
> > index 72553506a00b..13e9fc961d3b 100644
> > --- a/drivers/mtd/spi-nor/stm32-quadspi.c
> > +++ b/drivers/mtd/spi-nor/stm32-quadspi.c
> > @@ -355,7 +355,7 @@ static int stm32_qspi_read_reg(struct spi_nor *nor,
> >  	struct device *dev = flash->qspi->dev;
> >  	struct stm32_qspi_cmd cmd;
> >  
> > -	dev_dbg(dev, "read_reg: cmd:%#.2x buf:%p len:%#x\n", opcode, buf, len);
> > +	dev_dbg(dev, "read_reg: cmd:%#.2x buf:%pK len:%#x\n", opcode, buf, len);
> >  
> >  	memset(&cmd, 0, sizeof(cmd));
> >  	cmd.opcode = opcode;
> > @@ -376,7 +376,7 @@ static int stm32_qspi_write_reg(struct spi_nor *nor, u8 opcode,
> >  	struct device *dev = flash->qspi->dev;
> >  	struct stm32_qspi_cmd cmd;
> >  
> > -	dev_dbg(dev, "write_reg: cmd:%#.2x buf:%p len:%#x\n", opcode, buf, len);
> > +	dev_dbg(dev, "write_reg: cmd:%#.2x buf:%pK len:%#x\n", opcode, buf, len);
> >  
> >  	memset(&cmd, 0, sizeof(cmd));
> >  	cmd.opcode = opcode;
> > @@ -398,7 +398,7 @@ static ssize_t stm32_qspi_read(struct spi_nor *nor, loff_t from, size_t len,
> >  	struct stm32_qspi_cmd cmd;
> >  	int err;
> >  
> > -	dev_dbg(qspi->dev, "read(%#.2x): buf:%p from:%#.8x len:%#zx\n",
> > +	dev_dbg(qspi->dev, "read(%#.2x): buf:%pK from:%#.8x len:%#zx\n",
> >  		nor->read_opcode, buf, (u32)from, len);
> >  
> >  	memset(&cmd, 0, sizeof(cmd));
> >   
> 
>