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p2sb_bar() unhides P2SB device to get resources from the device. It
guards the operation by locking pci_rescan_remove_lock so that parallel
rescans do not find the P2SB device. However, this lock causes deadlock
when PCI bus rescan is triggered by /sys/bus/pci/rescan. The rescan
locks pci_rescan_remove_lock and probes PCI devices. When PCI devices
call p2sb_bar() during probe, it locks pci_rescan_remove_lock again.
Hence the deadlock.
To avoid the deadlock, do not lock pci_rescan_remove_lock in p2sb_bar().
Instead, do the lock at fs_initcall. Introduce p2sb_cache_resources()
for fs_initcall which gets and caches the P2SB resources. At p2sb_bar(),
refer the cache and return to the caller.
Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Fixes: 9745fb0747 ("platform/x86/intel: Add Primary to Sideband (P2SB) bridge support")
Cc: stable@vger.kernel.org
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/linux-pci/6xb24fjmptxxn5js2fjrrddjae6twex5bjaftwqsuawuqqqydx@7cl3uik5ef6j/
Link: https://lore.kernel.org/r/20231229063912.2517922-2-shinichiro.kawasaki@wdc.com
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
We have accessing P2SB from a very few places for quite known hardware.
When a new SoC appears in intel-family.h it's not obvious that it needs
to be added to p2sb.c as well. Instead, provide default BDF and refactor
p2sb_get_devfn() to always succeed. If in the future we would need to
exclude something, we may add a list of unsupported IDs.
Without this change the iTCO on Intel Comet Lake SoCs became unavailable:
i801_smbus 0000:00:1f.4: failed to create iTCO device
Fixes: 5c7b9167dd ("i2c: i801: convert to use common P2SB accessor")
Reported-and-tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20221104154916.35231-1-andriy.shevchenko@linux.intel.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
We have to copy only selected fields from the original resource.
Because a PCI device will be removed immediately after getting
its resources, we may not use any allocated data, hence we may
not copy any pointers.
Consider the following scenario:
1/ a caller of p2sb_bar() gets the resource;
2/ the resource has been copied by platform_device_add_data()
in order to create a platform device;
3/ the platform device creation will call for the device driver's
->probe() as soon as a match found;
4/ the ->probe() takes given resources (see 2/) and tries to
access one of its field, i.e. 'name', in the
__devm_ioremap_resource() to create a pretty looking output;
5/ but the 'name' is a dangling pointer because p2sb_bar()
removed a PCI device, which 'name' had been copied to
the caller's memory.
6/ UAF (Use-After-Free) as a result.
Kudos to Mika for the initial analisys of the issue.
Fixes: 9745fb0747 ("platform/x86/intel: Add Primary to Sideband (P2SB) bridge support")
Reported-by: kernel test robot <oliver.sang@intel.com>
Suggested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Link: https://lore.kernel.org/linux-i2c/YvPCbnKqDiL2XEKp@xsang-OptiPlex-9020/
Link: https://lore.kernel.org/linux-i2c/YtjAswDKfiuDfWYs@xsang-OptiPlex-9020/
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20220901113406.65876-1-andriy.shevchenko@linux.intel.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
The P2SB library is used for various drivers, including server
platforms. That's why the dependency on X86_PLATFORM_DEVICES
seems superfluous.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20220718145328.14374-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
