-------------X++++++++++++++++++++X---------------------
diff --git a/drivers/pci/pcie/aer/aerdrv_core.c
b/drivers/pci/pcie/aer/aerdrv_core.c
index 0f4554e..05592aa 100644
--- a/drivers/pci/pcie/aer/aerdrv_core.c
+++ b/drivers/pci/pcie/aer/aerdrv_core.c
@@ -26,6 +26,7 @@
#include <linux/slab.h>
#include <linux/kfifo.h>
#include "aerdrv.h"
+#include "../../pci.h"
static bool forceload;
static bool nosourceid;
@@ -82,7 +82,7 @@ EXPORT_SYMBOL_GPL(pci_cleanup_aer_uncorrect_error_status);
static int add_error_device(struct aer_err_info *e_info, struct
pci_dev *dev)
{
if (e_info->error_dev_num < AER_MAX_MULTI_ERR_DEVICES) {
-e_info->dev[e_info->error_dev_num] = dev;
+e_info->dev[e_info->error_dev_num] = pci_dev_get(dev);
e_info->error_dev_num++;
return 0;
}
@@ -659,6 +659,9 @@ static int get_device_error_info(struct pci_dev
*dev, struct aer_err_info *info)
if (!pos)
return 1;
+ if (pci_dev_is_disconnected(dev))
+ return 0;
+
if (info->severity == AER_CORRECTABLE) {
pci_read_config_dword(dev, pos + PCI_ERR_COR_STATUS,
&info->status);
@@ -710,6 +713,8 @@ static inline void aer_process_err_devices(struct
pcie_device *p_device,
for (i = 0; i < e_info->error_dev_num && e_info->dev[i]; i++) {
if (get_device_error_info(e_info->dev[i], e_info))
handle_error_source(p_device, e_info->dev[i], e_info);
+
+ pci_dev_put(e_info->dev[i]);
}
}
-------------X++++++++++++++++++++X---------------------
Note: I have configured CONFIG_HOTPLUG_PCI_PCIE and CONFIG_HOTPLUG_PCI
as modules and loading in start up using script.
root@/proc/:~# cat config | grep -i HOT
CONFIG_TICK_ONESHOT=y
CONFIG_HOTPLUG=y
# CONFIG_MEMORY_HOTPLUG is not set
CONFIG_HOTPLUG_CPU=y
# CONFIG_BOOTPARAM_HOTPLUG_CPU0 is not set
# CONFIG_DEBUG_HOTPLUG_CPU0 is not set
CONFIG_ARCH_ENABLE_MEMORY_HOTPLUG=y
CONFIG_ACPI_HOTPLUG_CPU=y
CONFIG_HOTPLUG_PCI_PCIE=m
CONFIG_HOTPLUG_PCI=m
# CONFIG_HOTPLUG_PCI_CPCI is not set
# CONFIG_HOTPLUG_PCI_SHPC is not set
CONFIG_DM_SNAPSHOT=y
# CONFIG_USB_STORAGE_JUMPSHOT is not set
# CONFIG_TRACER_SNAPSHOT is not set
root@/proc/:~#
Panic back trace :
crash> bt
PID: 24 TASK: ffff880274ac0000 CPU: 0 COMMAND: "kworker/0:1"
#0 [ffff880274abbac8] machine_kexec at ffffffff8102cf18
#1 [ffff880274abbb28] crash_kexec at ffffffff810a6b05
#2 [ffff880274abbbf0] oops_end at ffffffff8176d8a0
#3 [ffff880274abbc18] die at ffffffff810060db
#4 [ffff880274abbc48] do_general_protection at ffffffff8176d392
#5 [ffff880274abbc70] general_protection at ffffffff8176cd32
[exception RIP: pci_bus_read_config_dword+100]
RIP: ffffffff813405f4 RSP: ffff880274abbd20 RFLAGS: 00010046
RAX: 435f494350006963 RBX: ffff880274891800 RCX: 0000000000000004
RDX: 0000000000000ffc RSI: 0000000000000060 RDI: ffff880274891800
RBP: ffff880274abbd48 R8: ffff880274abbd2c R9: 00000000000002b8
R10: ffff880274340000 R11: 0000000000000246 R12: ffff880274abbd5c
R13: 0000000000000246 R14: 0000000000000000 R15: ffff880274920000
ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018
#6 [ffff880274abbd50] pci_find_next_ext_capability at ffffffff81345db6
#7 [ffff880274abbd90] pci_find_ext_capability at ffffffff81347225
#8 [ffff880274abbda0] get_device_error_info at ffffffff81356c4d
#9 [ffff880274abbdd0] aer_isr at ffffffff81357ab0
#10 [ffff880274abbe28] process_one_work at ffffffff8105d4c0
#11 [ffff880274abbe70] worker_thread at ffffffff8105e251
#12 [ffff880274abbed0] kthread at ffffffff81064260
#13 [ffff880274abbf50] ret_from_fork at ffffffff81773978
crash>
Regards,
Gokul
On Thu, Aug 2, 2018 at 10:39 PM, Thomas Tai <thomas.tai@xxxxxxxxxx
<mailto:thomas.tai@xxxxxxxxxx>> wrote:
On 08/02/2018 11:07 AM, Lukas Wunner wrote:
[cc += Thomas Tai]
Hi Lukas,
Thank you very much for cc me.
On Thu, Aug 02, 2018 at 10:46:57AM +0200, Lukas Wunner wrote:
On Thu, Aug 02, 2018 at 12:59:18PM +0530, gokul cg wrote:
I am suspecting a possible race condition in the kernel
between PCI driver
and AER handling.
The solution is to acquire a ref on each device in
add_error_device().
Then release the ref aer_process_err_devices() by calling
pci_dev_put().
So in case it wasn't clear, the below is what I had in mind.
Completely untested though. Does this work for you?
For v3.10 compatibility, cherry-pick 89ee9f768003 (or alternatively
cherry-pick 8496e85c20e7 and replace pci_dev_is_disconnected(dev)
with !pci_device_is_present(dev)).
-- >8 --
Subject: [PATCH] PCI/AER: Fix use-after-free on surprise removal
The work item to consume errors, aer_isr(), walks the hierarchy
using
pci_walk_bus() and stores a pointer to PCI devices which reported an
error in an array. As long as pci_walk_bus() runs, those
pointers are
valid because pci_bus_sem is held. But once pci_walk_bus()
finishes,
nothing prevents the pointers from becoming invalid, e.g. through
unplugging of the PCI devices. The unprotected pointers are then
dereferenced in aer_process_err_devices(), which may oops:
I like your idea to increment the refcount during pci_walk_bus(),
that should fix the use-after-free issue. We just need Gokul to
confirm if it fixes his issue or not.
Thanks,
Thomas
#5 general_protection at ffffffff8176cdf2
[exception RIP: pci_bus_read_config_dword+100]
#6 pci_find_next_ext_capability at ffffffff81345d7b
#7 pci_find_ext_capability at ffffffff81347225
#8 get_device_error_info at ffffffff81356c4d
#9 aer_isr at ffffffff81357a38
Fix by holding a ref on the devices until they have been processed.
Skip processing of unplugged devices.
Reported-by: gokul cg <gokuljnpr@xxxxxxxxx
<mailto:gokuljnpr@xxxxxxxxx>>
Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx
<mailto:lukas@xxxxxxxxx>>
---
drivers/pci/pcie/aer.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
index a2e8838..937592e 100644
--- a/drivers/pci/pcie/aer.c
+++ b/drivers/pci/pcie/aer.c
@@ -657,7 +657,7 @@ void cper_print_aer(struct pci_dev *dev, int
aer_severity,
static int add_error_device(struct aer_err_info *e_info,
struct pci_dev *dev)
{
if (e_info->error_dev_num < AER_MAX_MULTI_ERR_DEVICES) {
- e_info->dev[e_info->error_dev_num] = dev;
+ e_info->dev[e_info->error_dev_num] =
pci_dev_get(dev);
e_info->error_dev_num++;
return 0;
}
@@ -898,6 +898,9 @@ static int get_device_error_info(struct
pci_dev *dev, struct aer_err_info *info)
if (!pos)
return 0;
+ if (pci_dev_is_disconnected(dev))
+ return 0;
+
if (info->severity == AER_CORRECTABLE) {
pci_read_config_dword(dev, pos +
PCI_ERR_COR_STATUS,
&info->status);
@@ -948,6 +951,7 @@ static inline void
aer_process_err_devices(struct aer_err_info *e_info)
for (i = 0; i < e_info->error_dev_num &&
e_info->dev[i]; i++) {
if (get_device_error_info(e_info->dev[i], e_info))
handle_error_source(e_info->dev[i],
e_info);
+ pci_dev_put(e_info->dev[i]);
}
}
