linux-kernel - Re: Re: [PATCH v4] PCI: rcar-ep: Fix the issue of the name parameter when calling devm_request_mem

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Message-ID: <tencent_D3EAA236B531BDF17998832CC18EC36CBC07@qq.com>
Date: Wed,  8 Jan 2025 12:59:11 +0800
From: kingdix10@...com
To: helgaas@...nel.org
Cc: bhelgaas@...gle.com,
	kingdix10@...com,
	kw@...ux.com,
	linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org,
	linux-renesas-soc@...r.kernel.org,
	lpieralisi@...nel.org,
	manivannan.sadhasivam@...aro.org,
	marek.vasut+renesas@...il.com,
	prabhakar.csengg@...il.com,
	prabhakar.mahadev-lad.rj@...renesas.com,
	robh@...nel.org,
	yoshihiro.shimoda.uh@...esas.com
Subject: Re: Re: [PATCH v4] PCI: rcar-ep: Fix the issue of the name parameter when calling devm_request_mem_region

On Tue, 2025-01-07 at 16:56 -0600, Bjorn Helgaas wrote:
> On Tue, Jan 07, 2025 at 09:51:23PM +0800, kingdix10@...com wrote:
> > From: King Dix <kingdix10@...com>
> > 
> > When using devm_request_mem_region to request a resource, if the
> > passed
> > variable is a stack string variable, it will lead to an oops issue
> > when
> > executing the command cat /proc/iomem.
> > 
> > Fix this by replacing outbound_name with the name of the previously
> > requested resource.
> 
> Thanks a lot for doing this work!
> 
> Add "()" after function names in subject and commit log.
> 

Thanks for your review. I will fix the issue right now.

> Please include a couple lines of the oops message to help people
> connect the problem with the fix.
> 

This is a potential issue that I found while analyzing the code. I don't
have the conditions to reproduce this issue, but I can write a driver to
reproduce this issue in QEMU and obtain logs for reference.

> I suppose you found this by tripping over it.  Can you look through
> the other callers of devm_request_mem_region() and similar
> interfaces,
> at least in drivers/pci, and make sure there are no other similar
> errors?
> 

I've already checked that there are only a few calls of 
devm_request_mem_region() under the drivers/pci directory, and they
are all correct. 

> > Fixes: 2a6d0d63d999 ("PCI: rcar: Add endpoint mode support")
> > 
> > Signed-off-by: King Dix <kingdix10@...com>
> > Reviewed-by: Lad Prabhakar
> > <prabhakar.mahadev-lad.rj@...renesas.com>
> > Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> > ---
> > Changes in v4:
> >   - Add more information to the comment.
> > Changes in v3:
> >   - Fix the spelling issue in the comment.
> > Changes in v2:
> >   - Fix the code indentation issue.
> > ---
> >  drivers/pci/controller/pcie-rcar-ep.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/pci/controller/pcie-rcar-ep.c
> > b/drivers/pci/controller/pcie-rcar-ep.c
> > index 047e2cef5afc..c5e0d025bc43 100644
> > --- a/drivers/pci/controller/pcie-rcar-ep.c
> > +++ b/drivers/pci/controller/pcie-rcar-ep.c
> > @@ -107,7 +107,7 @@ static int
> > rcar_pcie_parse_outbound_ranges(struct rcar_pcie_endpoint *ep,
> >  		}
> >  		if (!devm_request_mem_region(&pdev->dev, res->start,
> >  					     resource_size(res),
> > -					     outbound_name)) {
> > +					     res->name)) {
> >  			dev_err(pcie->dev, "Cannot request memory region %s.\n",
> >  				outbound_name);
> >  			return -EIO;
> > -- 
> > 2.43.0
> >