答复: [????] Re: [PATCH] iommu/amd: Fix undefined behavior in devid_write debugfs function

["Li,Rongqing" <lirongqing@baidu.com>]

> 
> On Mon, Jun 01, 2026 at 08:12:40AM -0400, lirongqing wrote:
> > From: Li RongQing <lirongqing@baidu.com>
> >
> > When for_each_pci_segment() loop completes without finding a matching
> > segment, the pci_seg pointer is not NULL but points to an invalid
> > memory location (the list head). Accessing pci_seg->id after the loop
> > causes undefined behavior.
> >
> > Fix this by handling the successful case inside the loop and returning
> > -EINVAL after the loop if no matching segment is found.
> >
> > Fixes: 2e98940f123d9 ("iommu/amd: Add support for device id user
> > input")
> > Signed-off-by: Li RongQing <lirongqing@baidu.com>
> 
> Hi,
> 
> Thanks for the fix. Looks good to me.
> 
> Reviewed-by: Ankit Soni <Ankit.Soni@amd.com>
> 

Ping

[Li,Rongqing] 


> > ---
> >  drivers/iommu/amd/debugfs.c | 12 +++---------
> >  1 file changed, 3 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/iommu/amd/debugfs.c b/drivers/iommu/amd/debugfs.c
> > index 4c53b63..5c573ec 100644
> > --- a/drivers/iommu/amd/debugfs.c
> > +++ b/drivers/iommu/amd/debugfs.c
> > @@ -176,19 +176,13 @@ static ssize_t devid_write(struct file *filp, const
> char __user *ubuf,
> >  			kfree(srcid_ptr);
> >  			return -ENODEV;
> >  		}
> > -		break;
> > -	}
> > -
> > -	if (pci_seg->id != seg) {
> > +		sbdf = PCI_SEG_DEVID_TO_SBDF(seg, devid);
> >  		kfree(srcid_ptr);
> > -		return -EINVAL;
> > +		return cnt;
> >  	}
> >
> > -	sbdf = PCI_SEG_DEVID_TO_SBDF(seg, devid);
> > -
> >  	kfree(srcid_ptr);
> > -
> > -	return cnt;
> > +	return -EINVAL;
> >  }
> >
> >  static int devid_show(struct seq_file *m, void *unused)
> > --
> > 2.9.4
> >