ACK: [SRU][N][PATCH 0/1] CVE-2024-58093

[Chia-Lin Kao (AceLan)]

On Mon, Jun 23, 2025 at 08:30:58PM +0900, Masahiro Yamada wrote:
> [Impact]
> 
>     PCI/ASPM: Fix link state exit during switch upstream function removal
>     
>     Before 456d8aa37d0f ("PCI/ASPM: Disable ASPM on MFD function removal to
>     avoid use-after-free"), we would free the ASPM link only after the last
>     function on the bus pertaining to the given link was removed.
>     
>     That was too late. If function 0 is removed before sibling function,
>     link->downstream would point to free'd memory after.
>     
>     After above change, we freed the ASPM parent link state upon any function
>     removal on the bus pertaining to a given link.
>     
>     That is too early. If the link is to a PCIe switch with MFD on the upstream
>     port, then removing functions other than 0 first would free a link which
>     still remains parent_link to the remaining downstream ports.
>     
>     The resulting GPFs are especially frequent during hot-unplug, because
>     pciehp removes devices on the link bus in reverse order.
>     
>     On that switch, function 0 is the virtual P2P bridge to the internal bus.
>     Free exactly when function 0 is removed -- before the parent link is
>     obsolete, but after all subordinate links are gone.
> 
> [Fix]
> 
> Noble:    Sent to ML (this patch set)
> Jammy:    Backported (WIP
> Focal:    Fixed already
> Bionic:   Not affected
> Xenial:   Not affected
> Trusty:   Not affected
> 
> [Test Case]
> 
> Compile and boot tested. 'lspci' was OK.
> 
> [Where problems could occur]
> 
> This fix affects PCIe.
> 
> Daniel Stodden (1):
>   PCI/ASPM: Fix link state exit during switch upstream function removal
> 
>  drivers/pci/pcie/aspm.c | 17 +++++++++--------
>  1 file changed, 9 insertions(+), 8 deletions(-)
> 
> -- 
> 2.43.0
Acked-by: Chia-Lin Kao (AceLan) <acelan.kao at canonical.com>
> 
> 
> -- 
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