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| author | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2016-01-25 19:08:00 +0300 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2016-02-27 17:28:43 +0300 |
| commit | 94d2d14172d0334d5fa53c9c20a1aef295c8fbcc (patch) | |
| tree | d413af7cd17cc3c1ad6f9df587cb369b9625e92c | |
| parent | 8c0726c844369f81f56c10ba72e6fc1bd638f530 (diff) | |
| download | linux-94d2d14172d0334d5fa53c9c20a1aef295c8fbcc.tar.xz | |
PCI/AER: Flush workqueue on device remove to avoid use-after-free
commit 4ae2182b1e3407de369f8c5d799543b7db74221b upstream.
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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
| -rw-r--r-- | drivers/pci/pcie/aer/aerdrv.c | 4 | ||||
| -rw-r--r-- | drivers/pci/pcie/aer/aerdrv.h | 1 | ||||
| -rw-r--r-- | drivers/pci/pcie/aer/aerdrv_core.c | 2 |
3 files changed, 1 insertions, 6 deletions
diff --git a/drivers/pci/pcie/aer/aerdrv.c b/drivers/pci/pcie/aer/aerdrv.c index 58ad7917553c..8cc54f24d0aa 100644 --- a/drivers/pci/pcie/aer/aerdrv.c +++ b/drivers/pci/pcie/aer/aerdrv.c @@ -263,7 +263,6 @@ static struct aer_rpc *aer_alloc_rpc(struct pcie_device *dev) rpc->rpd = dev; INIT_WORK(&rpc->dpc_handler, aer_isr); mutex_init(&rpc->rpc_mutex); - init_waitqueue_head(&rpc->wait_release); /* Use PCIe bus function to store rpc into PCIe device */ set_service_data(dev, rpc); @@ -286,8 +285,7 @@ static void aer_remove(struct pcie_device *dev) if (rpc->isr) free_irq(dev->irq, dev); - wait_event(rpc->wait_release, rpc->prod_idx == rpc->cons_idx); - + flush_work(&rpc->dpc_handler); aer_disable_rootport(rpc); kfree(rpc); set_service_data(dev, NULL); diff --git a/drivers/pci/pcie/aer/aerdrv.h b/drivers/pci/pcie/aer/aerdrv.h index 94a7598eb262..9c611f1bc56a 100644 --- a/drivers/pci/pcie/aer/aerdrv.h +++ b/drivers/pci/pcie/aer/aerdrv.h @@ -76,7 +76,6 @@ struct aer_rpc { * recovery on the same * root port hierarchy */ - wait_queue_head_t wait_release; }; struct aer_broadcast_data { diff --git a/drivers/pci/pcie/aer/aerdrv_core.c b/drivers/pci/pcie/aer/aerdrv_core.c index ee82c559092a..21addfa2f89e 100644 --- a/drivers/pci/pcie/aer/aerdrv_core.c +++ b/drivers/pci/pcie/aer/aerdrv_core.c @@ -823,8 +823,6 @@ void aer_isr(struct work_struct *work) while (get_e_source(rpc, &e_src)) aer_isr_one_error(p_device, &e_src); mutex_unlock(&rpc->rpc_mutex); - - wake_up(&rpc->wait_release); } /** |