From: Tong Zhang <ztong0001@gmail.com>
To: Arnd Bergmann <arnd@arndb.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Tong Zhang <ztong0001@gmail.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH v3] misc: alcor_pci: fix null-ptr-deref when there is no PCI bridge
Date: Thu, 13 May 2021 00:07:33 -0400 [thread overview]
Message-ID: <20210513040732.1310159-1-ztong0001@gmail.com> (raw)
In-Reply-To: <YJwFLgvgIXHn8Zch@kroah.com>
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>
---
v2: check before calling alcor_pci_find_cap_offset()
v3: Add comment. Enable the dev_dbg() output when priv->parent_pdev is NULL.
drivers/misc/cardreader/alcor_pci.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/misc/cardreader/alcor_pci.c b/drivers/misc/cardreader/alcor_pci.c
index cd402c89189e..0a62307f7ffb 100644
--- a/drivers/misc/cardreader/alcor_pci.c
+++ b/drivers/misc/cardreader/alcor_pci.c
@@ -139,7 +139,13 @@ static void alcor_pci_init_check_aspm(struct alcor_pci_priv *priv)
u32 val32;
priv->pdev_cap_off = alcor_pci_find_cap_offset(priv, priv->pdev);
- priv->parent_cap_off = alcor_pci_find_cap_offset(priv,
+ /*
+ * A device might be attached to root complex directly and
+ * priv->parent_pdev will be NULL. In this case we don't check its
+ * capability and disable ASPM completely.
+ */
+ if (!priv->parent_pdev)
+ priv->parent_cap_off = alcor_pci_find_cap_offset(priv,
priv->parent_pdev);
if ((priv->pdev_cap_off == 0) || (priv->parent_cap_off == 0)) {
--
2.25.1
next prev parent reply other threads:[~2021-05-13 4:08 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-26 22:07 [PATCH] misc: alcor_pci: fix null-ptr-deref when there is no PCI bridge Tong Zhang
2021-05-10 14:36 ` Greg Kroah-Hartman
2021-05-10 22:20 ` Tong Zhang
2021-05-11 7:03 ` Greg Kroah-Hartman
2021-05-11 17:17 ` Tong Zhang
2021-05-11 17:57 ` Greg Kroah-Hartman
2021-05-11 21:29 ` [PATCH v2] " Tong Zhang
2021-05-12 6:24 ` Greg Kroah-Hartman
2021-05-12 16:24 ` Tong Zhang
2021-05-12 16:41 ` Greg Kroah-Hartman
2021-05-13 4:07 ` Tong Zhang [this message]
2021-05-19 8:40 ` [PATCH v3] " Dan Carpenter
2021-05-19 20:20 ` Tong Zhang
2021-05-13 4:09 ` [PATCH v2] " Tong Zhang
2021-05-11 21:32 ` [PATCH] " Tong Zhang
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