From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Tong Zhang <ztong0001@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>,
linux-kernel@vger.kernel.org,
Colin Ian King <colin.king@canonical.com>
Subject: Re: [PATCH v4] misc: alcor_pci: fix null-ptr-deref when there is no PCI bridge
Date: Fri, 21 May 2021 14:44:13 +0200 [thread overview]
Message-ID: <YKerHVMuqnRQmhMz@kroah.com> (raw)
In-Reply-To: <20210518192820.181500-1-ztong0001@gmail.com>
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
next prev parent reply other threads:[~2021-05-21 12:44 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-18 18:32 misc: alcor_pci: fix null-ptr-deref when there is no PCI bridge Colin Ian King
2021-05-18 19:22 ` Tong Zhang
2021-05-18 19:28 ` [PATCH v4] " Tong Zhang
2021-05-21 12:44 ` Greg Kroah-Hartman [this message]
2021-05-21 14:51 ` Tong Zhang
2021-05-22 4:37 ` [PATCH v1] misc: alcor_pci: fix inverted branch condition Tong Zhang
2021-05-22 4:40 ` [PATCH v4] misc: alcor_pci: fix null-ptr-deref when there is no PCI bridge Tong Zhang
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