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
Cc: Colin Ian King <colin.king@canonical.com>
Subject: [PATCH v4] misc: alcor_pci: fix null-ptr-deref when there is no PCI bridge
Date: Tue, 18 May 2021 15:28:18 -0400 [thread overview]
Message-ID: <20210518192820.181500-1-ztong0001@gmail.com> (raw)
In-Reply-To: <cb099c69-0d59-7a12-b0bc-2ce71264363e@canonical.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>
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>
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..de6d44a158bb 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:[~2021-05-18 19:28 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 ` Tong Zhang [this message]
2021-05-21 12:44 ` [PATCH v4] " Greg Kroah-Hartman
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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