Re: commit 7b025f3f85ed causes NULL pointer dereference

[Venkat Rao Bagalkote <venkat88@linux.ibm.com>]

On 09/04/25 2:16 am, Thomas Gleixner wrote:
> On Tue, Apr 08 2025 at 18:20, Bert Karwatzki wrote:
>> Am Dienstag, dem 08.04.2025 um 17:29 +0200 schrieb Thomas Gleixner:
>>>> Can you please decode the lines please via:
>>>>
>>>>      scripts/faddr2line vmlinux msi_domain_first_desc+0x4/0x30
>>>>      scripts/faddr2line vmlinux msix_setup_interrupts+0x23b/0x280
>> I had to recompile with CONFIG_DEBUG_INFO=Y, and reran the test, the calltrace
>> is identical.
>>
>> $ scripts/faddr2line vmlinux msi_domain_first_desc+0x4/0x30
>> msi_domain_first_desc+0x4/0x30:
>> msi_domain_first_desc at kernel/irq/msi.c:400
>>
>> So it seems msi_domain_first_desc() is called with dev = NULL.


This issue is seen on IBM Power9 server also. Bisection is pointing to 
7b025f3f85ed4283d5a414371bb2ffd38d19033f as first bad commit.

I applied this patch on top of 20250409 and it fixes the issue.


> Yup
>
>> $ scripts/faddr2line vmlinux msix_setup_interrupts+0x23b/0x280
>> msix_setup_interrupts+0x23b/0x280:
>> msix_update_entries at drivers/pci/msi/msi.c:647 (discriminator 1)
> Aaarg. The patch below should fix that.
>
> Thanks,
>
>          tglx
> ---
> diff --git a/drivers/pci/msi/msi.c b/drivers/pci/msi/msi.c
> index 4027abcafe7a..77cc27e45b66 100644
> --- a/drivers/pci/msi/msi.c
> +++ b/drivers/pci/msi/msi.c
> @@ -680,8 +680,8 @@ static int __msix_setup_interrupts(struct pci_dev *__dev, struct msix_entry *ent
>   	if (ret)
>   		return ret;
>   
> -	retain_ptr(dev);
>   	msix_update_entries(dev, entries);
> +	retain_ptr(dev);
>   	return 0;
>   }
>   

Reported-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>

Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>


Regards,

Venkat.