| From 20d591329b2e5c8de1553b7eacf535f767b4a75b Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Thu, 13 May 2021 00:07:33 -0400 |
| Subject: misc: alcor_pci: fix null-ptr-deref when there is no PCI bridge |
| |
| From: Tong Zhang <ztong0001@gmail.com> |
| |
| [ Upstream commit 3ce3e45cc333da707d4d6eb433574b990bcc26f5 ] |
| |
| 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] |
| |
| Co-developed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| Signed-off-by: Tong Zhang <ztong0001@gmail.com> |
| Link: https://lore.kernel.org/r/20210513040732.1310159-1-ztong0001@gmail.com |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| 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)) { |
| -- |
| 2.30.2 |
| |