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A Root Port's AER structure (rpc) contains a queue of events. aer_irq()
enqueues AER status information and schedules aer_isr() to dequeue and
process it. When we remove a device, aer_remove() waits for the queue to
be empty, then frees the rpc struct.
But aer_isr() references the rpc struct after dequeueing and possibly
emptying the queue, which can cause a use-after-free error as in the
following scenario with two threads, aer_isr() on the left and a
concurrent aer_remove() on the right:
Thread A Thread B
-------- --------
aer_irq():
rpc->prod_idx++
aer_remove():
wait_event(rpc->prod_idx == rpc->cons_idx)
# now blocked until queue becomes empty
aer_isr(): # ...
rpc->cons_idx++ # unblocked because queue is now empty
... kfree(rpc)
mutex_unlock(&rpc->rpc_mutex)
To prevent this problem, use flush_work() to wait until the last scheduled
instance of aer_isr() has completed before freeing the rpc struct in
aer_remove().
I reproduced this use-after-free by flashing a device FPGA and
re-enumerating the bus to find the new device. With SLUB debug, this
crashes with 0x6b bytes (POISON_FREE, the use-after-free magic number) in
GPR25:
pcieport 0000:00:00.0: AER: Multiple Corrected error received: id=0000
Unable to handle kernel paging request for data at address 0x27ef9e3e
Workqueue: events aer_isr
GPR24: dd6aa000 6b6b6b6b 605f8378 605f8360 d99b12c0 604fc674 606b1704 d99b12c0
NIP [602f5328] pci_walk_bus+0xd4/0x104
[bhelgaas: changelog, stable tag]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: stable@vger.kernel.org
132 lines
3.3 KiB
C
132 lines
3.3 KiB
C
/*
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* Copyright (C) 2006 Intel Corp.
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* Tom Long Nguyen (tom.l.nguyen@intel.com)
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* Zhang Yanmin (yanmin.zhang@intel.com)
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*
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*/
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#ifndef _AERDRV_H_
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#define _AERDRV_H_
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#include <linux/workqueue.h>
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#include <linux/pcieport_if.h>
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#include <linux/aer.h>
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#include <linux/interrupt.h>
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#define SYSTEM_ERROR_INTR_ON_MESG_MASK (PCI_EXP_RTCTL_SECEE| \
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PCI_EXP_RTCTL_SENFEE| \
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PCI_EXP_RTCTL_SEFEE)
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#define ROOT_PORT_INTR_ON_MESG_MASK (PCI_ERR_ROOT_CMD_COR_EN| \
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PCI_ERR_ROOT_CMD_NONFATAL_EN| \
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PCI_ERR_ROOT_CMD_FATAL_EN)
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#define ERR_COR_ID(d) (d & 0xffff)
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#define ERR_UNCOR_ID(d) (d >> 16)
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#define AER_ERROR_SOURCES_MAX 100
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#define AER_LOG_TLP_MASKS (PCI_ERR_UNC_POISON_TLP| \
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PCI_ERR_UNC_ECRC| \
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PCI_ERR_UNC_UNSUP| \
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PCI_ERR_UNC_COMP_ABORT| \
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PCI_ERR_UNC_UNX_COMP| \
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PCI_ERR_UNC_MALF_TLP)
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#define AER_MAX_MULTI_ERR_DEVICES 5 /* Not likely to have more */
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struct aer_err_info {
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struct pci_dev *dev[AER_MAX_MULTI_ERR_DEVICES];
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int error_dev_num;
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unsigned int id:16;
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unsigned int severity:2; /* 0:NONFATAL | 1:FATAL | 2:COR */
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unsigned int __pad1:5;
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unsigned int multi_error_valid:1;
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unsigned int first_error:5;
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unsigned int __pad2:2;
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unsigned int tlp_header_valid:1;
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unsigned int status; /* COR/UNCOR Error Status */
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unsigned int mask; /* COR/UNCOR Error Mask */
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struct aer_header_log_regs tlp; /* TLP Header */
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};
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struct aer_err_source {
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unsigned int status;
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unsigned int id;
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};
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struct aer_rpc {
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struct pcie_device *rpd; /* Root Port device */
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struct work_struct dpc_handler;
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struct aer_err_source e_sources[AER_ERROR_SOURCES_MAX];
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unsigned short prod_idx; /* Error Producer Index */
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unsigned short cons_idx; /* Error Consumer Index */
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int isr;
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spinlock_t e_lock; /*
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* Lock access to Error Status/ID Regs
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* and error producer/consumer index
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*/
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struct mutex rpc_mutex; /*
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* only one thread could do
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* recovery on the same
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* root port hierarchy
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*/
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};
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struct aer_broadcast_data {
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enum pci_channel_state state;
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enum pci_ers_result result;
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};
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static inline pci_ers_result_t merge_result(enum pci_ers_result orig,
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enum pci_ers_result new)
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{
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if (new == PCI_ERS_RESULT_NO_AER_DRIVER)
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return PCI_ERS_RESULT_NO_AER_DRIVER;
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if (new == PCI_ERS_RESULT_NONE)
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return orig;
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switch (orig) {
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case PCI_ERS_RESULT_CAN_RECOVER:
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case PCI_ERS_RESULT_RECOVERED:
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orig = new;
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break;
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case PCI_ERS_RESULT_DISCONNECT:
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if (new == PCI_ERS_RESULT_NEED_RESET)
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orig = PCI_ERS_RESULT_NEED_RESET;
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break;
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default:
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break;
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}
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return orig;
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}
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extern struct bus_type pcie_port_bus_type;
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int aer_init(struct pcie_device *dev);
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void aer_isr(struct work_struct *work);
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void aer_print_error(struct pci_dev *dev, struct aer_err_info *info);
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void aer_print_port_info(struct pci_dev *dev, struct aer_err_info *info);
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irqreturn_t aer_irq(int irq, void *context);
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#ifdef CONFIG_ACPI_APEI
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int pcie_aer_get_firmware_first(struct pci_dev *pci_dev);
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#else
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static inline int pcie_aer_get_firmware_first(struct pci_dev *pci_dev)
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{
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if (pci_dev->__aer_firmware_first_valid)
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return pci_dev->__aer_firmware_first;
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return 0;
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}
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#endif
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static inline void pcie_aer_force_firmware_first(struct pci_dev *pci_dev,
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int enable)
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{
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pci_dev->__aer_firmware_first = !!enable;
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pci_dev->__aer_firmware_first_valid = 1;
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}
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#endif /* _AERDRV_H_ */
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