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| author | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2016-01-25 10:08:00 -0600 |
|---|---|---|
| committer | Willy Tarreau <w@1wt.eu> | 2016-03-12 14:25:41 +0100 |
| commit | c5ab1213c68ef67e37cef0159ad081424f54ed19 (patch) | |
| tree | bfe4b9b607382cf65ea67507e5d12f8b0b612a6c | |
| parent | 2a890807f49093b129357e830e8dd949e3eb4514 (diff) | |
| download | linux-c5ab1213c68ef67e37cef0159ad081424f54ed19.tar.gz linux-c5ab1213c68ef67e37cef0159ad081424f54ed19.tar.bz2 linux-c5ab1213c68ef67e37cef0159ad081424f54ed19.zip | |
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>
[wt: in 2.6.32, kfree() is called from aer_delete_rootport()]
Signed-off-by: Willy Tarreau <w@1wt.eu>
| -rw-r--r-- | drivers/pci/pcie/aer/aerdrv.c | 3 | ||||
| -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, 5 deletions
diff --git a/drivers/pci/pcie/aer/aerdrv.c b/drivers/pci/pcie/aer/aerdrv.c index 40c3cc5d1caf..8d8bef35f12f 100644 --- a/drivers/pci/pcie/aer/aerdrv.c +++ b/drivers/pci/pcie/aer/aerdrv.c @@ -153,7 +153,6 @@ static struct aer_rpc *aer_alloc_rpc(struct pcie_device *dev) INIT_WORK(&rpc->dpc_handler, aer_isr); rpc->prod_idx = rpc->cons_idx = 0; 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); @@ -176,7 +175,7 @@ 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_delete_rootport(rpc); set_service_data(dev, NULL); diff --git a/drivers/pci/pcie/aer/aerdrv.h b/drivers/pci/pcie/aer/aerdrv.h index bd833ea3ba49..ef6163f2b549 100644 --- a/drivers/pci/pcie/aer/aerdrv.h +++ b/drivers/pci/pcie/aer/aerdrv.h @@ -86,7 +86,6 @@ 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 72fa87c095d8..093045a38e80 100644 --- a/drivers/pci/pcie/aer/aerdrv_core.c +++ b/drivers/pci/pcie/aer/aerdrv_core.c @@ -844,8 +844,6 @@ void aer_isr(struct work_struct *work) e_src = get_e_source(rpc); } mutex_unlock(&rpc->rpc_mutex); - - wake_up(&rpc->wait_release); } /** |