diff options
| author | Yinghai Lu <yinghai@kernel.org> | 2017-03-01 00:25:40 -0800 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2017-03-07 14:23:30 -0600 |
| commit | 3bd7db63a841e8c5297bb18ad801df67d5e38ad2 (patch) | |
| tree | 0cb060a88adc65c6e3ffb25305a60eafa11b21c5 /drivers/pci/pcie/aspm.c | |
| parent | 0d5370d1d85251e5893ab7c90a429464de2e140b (diff) | |
| download | lwn-3bd7db63a841e8c5297bb18ad801df67d5e38ad2.tar.gz lwn-3bd7db63a841e8c5297bb18ad801df67d5e38ad2.zip | |
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/pcie/aspm.c')
| -rw-r--r-- | drivers/pci/pcie/aspm.c | 5 |
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 |