From: Dan Carpenter <dan.carpenter@oracle.com>
To: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Colin King <colin.king@canonical.com>,
Richard Weinberger <richard@nod.at>,
Vignesh Raghavendra <vigneshr@ti.com>,
linux-mtd@lists.infradead.org, kernel-janitors@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH][next] mtd: rawnand: ensure return variable is initialized
Date: Tue, 1 Jun 2021 15:14:02 +0300 [thread overview]
Message-ID: <20210601121401.GY1955@kadam> (raw)
In-Reply-To: <20210527170309.4d99bc31@xps13>
On Thu, May 27, 2021 at 05:03:09PM +0200, Miquel Raynal wrote:
> Hi Colin,
>
> Colin King <colin.king@canonical.com> wrote on Thu, 27 May 2021
> 15:50:48 +0100:
>
> > From: Colin Ian King <colin.king@canonical.com>
> >
> > Currently there are corner cases where spec_times is NULL and
> > chip->parameters.onfi or when best_mode is zero where ret is
>
> ^
> something is missing here, the sentence is not clear
>
> > not assigned a value and an uninitialized return value can be
> > returned. Fix this by ensuring ret is initialized to -EINVAL.
>
> I don't see how this situation can happen.
>
> In both cases, no matter the value of best_mode, the for loop will
> always execute at least one time (mode 0) so ret will be populated.
>
> Maybe the robot does not know that best_mode cannot be negative and
> should be defined unsigned, but the current patch is invalid.
>
People think list counter unsigned is a good idea, but it's a terrible
idea and has caused hundreds of bugs for me to fix/report over the
years. *grumble*.
Anyway, I was revisiting this code because it showed up as a Smatch
warning and the bug appears to be real.
best_mode = fls(chip->parameters.onfi->sdr_timing_modes) - 1;
The "onfi->sdr_timing_modes" comes from the hardware in nand_onfi_detect()
and nothing checks that it is non-zero so "best_mode = fls(0) - 1;" is
negative and "ret" is uninitialized.
regards,
dan carpenter
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next prev parent reply other threads:[~2021-06-01 12:15 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-27 14:50 [PATCH][next] mtd: rawnand: ensure return variable is initialized Colin King
2021-05-27 15:03 ` Miquel Raynal
2021-05-27 15:22 ` Colin Ian King
2021-06-01 12:14 ` Dan Carpenter [this message]
2021-06-01 12:58 ` Dan Carpenter
2021-06-07 6:57 ` Miquel Raynal
2021-06-08 6:10 ` Dan Carpenter
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