linux-kernel - Re: [PATCH next] nvdimm: Prevent integer overflow in ramdax_get_config

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Message-ID: <aSX8kcQT3z-iD94M@stanley.mountain>
Date: Tue, 25 Nov 2025 21:59:29 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Ira Weiny <ira.weiny@...el.com>
Cc: Mike Rapoport <rppt@...nel.org>,
	Dan Williams <dan.j.williams@...el.com>,
	Vishal Verma <vishal.l.verma@...el.com>,
	Dave Jiang <dave.jiang@...el.com>, nvdimm@...ts.linux.dev,
	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH next] nvdimm: Prevent integer overflow in
 ramdax_get_config_data()

On Tue, Nov 25, 2025 at 10:38:29AM -0600, Ira Weiny wrote:
> Dan Carpenter wrote:
> > The "cmd->in_offset" variable comes from the user via the __nd_ioctl()
> > function.  The problem is that the "cmd->in_offset + cmd->in_length"
> > addition could have an integer wrapping issue if cmd->in_offset is close
> > to UINT_MAX .  The "cmd->in_length" variable has been capped, but the
> > "cmd->in_offset" variable has not.  Both of these variables are type u32.
> 
> Does ramdax_set_config_data() also need this?

Yes.  It does.  These are from Smatch warnings, right.  They take a few
rebuilds for the taint information to propagate from the ioctl to the
ramdax_get_config_data() function.  When I rebuilt it, then it propagates
to both so I would have seen the ramdax_set_config_data() tomorrow.

But they're called from the same function so the taint data should
have propagated to both at the same time...  WTF?  I don't know what
happened.  Anyway, I will fix that and resend.

Thanks for noticing.

>  I'm not quite following where in_length is capped so I'm inclined to
> add size_add in both set and get.

I meant that the  if (struct_size(cmd, in_buf, cmd->in_length) > buf_len)
line checks that cmd->in_length is okay.

regards,
dan carpenter