Messages in this thread | | | Date | Fri, 21 May 2021 14:44:13 +0200 | From | Greg Kroah-Hartman <> | Subject | Re: [PATCH v4] misc: alcor_pci: fix null-ptr-deref when there is no PCI bridge |
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On Tue, May 18, 2021 at 03:28:18PM -0400, Tong Zhang wrote: > There is an issue with the ASPM(optional) capability checking function. > A device might be attached to root complex directly, in this case, > bus->self(bridge) will be NULL, thus priv->parent_pdev is NULL. > Since alcor_pci_init_check_aspm(priv->parent_pdev) checks the PCI link's > ASPM capability and populate parent_cap_off, which will be used later by > alcor_pci_aspm_ctrl() to dynamically turn on/off device, what we can do > here is to avoid checking the capability if we are on the root complex. > This will make pdev_cap_off 0 and alcor_pci_aspm_ctrl() will simply > return when bring called, effectively disable ASPM for the device. > > [ 1.246492] BUG: kernel NULL pointer dereference, address: 00000000000000c0 > [ 1.248731] RIP: 0010:pci_read_config_byte+0x5/0x40 > [ 1.253998] Call Trace: > [ 1.254131] ? alcor_pci_find_cap_offset.isra.0+0x3a/0x100 [alcor_pci] > [ 1.254476] alcor_pci_probe+0x169/0x2d5 [alcor_pci] > > Signed-off-by: Tong Zhang <ztong0001@gmail.com> > Co-developed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Co-developed-by: Colin Ian King <colin.king@canonical.com> > --- > v2: check before calling alcor_pci_find_cap_offset() > v3: Add comment. Enable the dev_dbg() output when priv->parent_pdev is NULL. > v4: fix inverted if statement, thanks to Colin <colin.king@canonical.com>
Please just send a fix-up patch instead, I don't want to revert and then add this, that doesn't make any sense...
thanks,
greg k-h
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