In the Linux kernel, the following vulnerability has been resolved:
PCI/ASPM: Fix deadlock when enabling ASPM
A last minute revert in 6.7-final introduced a potential deadlock when
enabling ASPM during probe of Qualcomm PCIe controllers as reported by
lockdep:
kworker/u16:5/90 is trying to acquire lock:
ffffacfa78ced000 (pci_bus_sem){++++}-{3:3}, at: pcie_aspm_pm_state_change+0x58/0xdc
but task is already holding lock:
ffffacfa78ced000 (pci_bus_sem){++++}-{3:3}, at: pci_walk_bus+0x34/0xbc
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(pci_bus_sem);
lock(pci_bus_sem);
*** DEADLOCK***
Call trace:
print_deadlock_bug+0x25c/0x348
__lock_acquire+0x10a4/0x2064
lock_acquire+0x1e8/0x318
down_read+0x60/0x184
pcie_aspm_pm_state_change+0x58/0xdc
pci_set_full_power_state+0xa8/0x114
pci_set_power_state+0xc4/0x120
qcom_pcie_enable_aspm+0x1c/0x3c [pcie_qcom]
pci_walk_bus+0x64/0xbc
qcom_pcie_host_post_init_2_7_0+0x28/0x34 [pcie_qcom]
The deadlock can easily be reproduced on machines like the Lenovo ThinkPad
X13s by adding a delay to increase the race window during asynchronous
probe where another thread can take a write lock.
Add a new pci_set_power_state_locked() and associated helper functions that
can be called with the PCI bus semaphore held to avoid taking the read lock
twice.
[
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "unaffected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"drivers/pci/bus.c",
"drivers/pci/controller/dwc/pcie-qcom.c",
"drivers/pci/pci.c",
"drivers/pci/pci.h",
"drivers/pci/pcie/aspm.c",
"include/linux/pci.h"
],
"versions": [
{
"version": "b9c370b61d73",
"lessThan": "0f7908a016c0",
"status": "affected",
"versionType": "git"
},
{
"version": "8cc22ba3f77c",
"lessThan": "b0f4478838be",
"status": "affected",
"versionType": "git"
},
{
"version": "f93e71aea6c6",
"lessThan": "ef90508574d7",
"status": "affected",
"versionType": "git"
},
{
"version": "f93e71aea6c6",
"lessThan": "1e560864159d",
"status": "affected",
"versionType": "git"
}
]
},
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "affected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"drivers/pci/bus.c",
"drivers/pci/controller/dwc/pcie-qcom.c",
"drivers/pci/pci.c",
"drivers/pci/pci.h",
"drivers/pci/pcie/aspm.c",
"include/linux/pci.h"
],
"versions": [
{
"version": "6.7",
"status": "affected"
},
{
"version": "0",
"lessThan": "6.7",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "6.1.88",
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "6.6.29",
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "6.7.5",
"lessThanOrEqual": "6.7.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "6.8",
"lessThanOrEqual": "*",
"status": "unaffected",
"versionType": "original_commit_for_fix"
}
]
}
]