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authorYinghai Lu <yinghai@kernel.org>2017-03-01 00:25:40 -0800
committerBjorn Helgaas <bhelgaas@google.com>2017-03-07 14:23:30 -0600
commit3bd7db63a841e8c5297bb18ad801df67d5e38ad2 (patch)
tree0cb060a88adc65c6e3ffb25305a60eafa11b21c5 /drivers/pci
parent0d5370d1d85251e5893ab7c90a429464de2e140b (diff)
downloadlinux-3bd7db63a841e8c5297bb18ad801df67d5e38ad2.tar.bz2
PCI/ASPM: Always set link->downstream to avoid NULL dereference on remove
We call pcie_aspm_exit_link_state() when we remove a device. If the device is the last PCIe function to be removed below a bridge and the bridge has an ASPM link_state struct, we disable ASPM on the link. Disabling ASPM requires link->downstream (used in pcie_config_aspm_link()). We previously set link->downstream in pcie_aspm_cap_init(), but only if the device was not blacklisted. Removing the blacklisted device caused a NULL pointer dereference in the pcie_aspm_exit_link_state() -> pcie_config_aspm_link() path: # echo 1 > /sys/bus/pci/devices/0000\:0b\:00.0/remove ... BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 IP: pcie_config_aspm_link+0x5d/0x2b0 Call Trace: pcie_aspm_exit_link_state+0x75/0x130 pci_stop_bus_device+0xa4/0xb0 pci_stop_and_remove_bus_device_locked+0x1a/0x30 remove_store+0x50/0x70 dev_attr_store+0x18/0x30 sysfs_kf_write+0x44/0x60 kernfs_fop_write+0x10e/0x190 __vfs_write+0x28/0x110 ? rcu_read_lock_sched_held+0x5d/0x80 ? rcu_sync_lockdep_assert+0x2c/0x60 ? __sb_start_write+0x173/0x1a0 ? vfs_write+0xb3/0x180 vfs_write+0xc4/0x180 SyS_write+0x49/0xa0 do_syscall_64+0xa6/0x1c0 entry_SYSCALL64_slow_path+0x25/0x25 ---[ end trace bd187ee0267df5d9 ]--- To avoid this, set link->downstream in alloc_pcie_link_state(), so every pcie_link_state structure has a valid link->downstream pointer. [bhelgaas: changelog] Signed-off-by: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Acked-by: Rajat Jain <rajatja@google.com> CC: stable@vger.kernel.org
Diffstat (limited to 'drivers/pci')
-rw-r--r--drivers/pci/pcie/aspm.c5
1 files changed, 2 insertions, 3 deletions
diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index 973472c23d89..1dfa10cc566b 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -478,7 +478,7 @@ static void aspm_calc_l1ss_info(struct pcie_link_state *link,
static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)
{
- struct pci_dev *child, *parent = link->pdev;
+ struct pci_dev *child = link->downstream, *parent = link->pdev;
struct pci_bus *linkbus = parent->subordinate;
struct aspm_register_info upreg, dwreg;
@@ -491,9 +491,7 @@ static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)
/* Get upstream/downstream components' register state */
pcie_get_aspm_reg(parent, &upreg);
- child = pci_function_0(linkbus);
pcie_get_aspm_reg(child, &dwreg);
- link->downstream = child;
/*
* If ASPM not supported, don't mess with the clocks and link,
@@ -800,6 +798,7 @@ static struct pcie_link_state *alloc_pcie_link_state(struct pci_dev *pdev)
INIT_LIST_HEAD(&link->children);
INIT_LIST_HEAD(&link->link);
link->pdev = pdev;
+ link->downstream = pci_function_0(pdev->subordinate);
/*
* Root Ports and PCI/PCI-X to PCIe Bridges are roots of PCIe