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Subject[PATCH v2] PCI/MSI: fix page fault when msi_populate_sysfs() failed
Date
I got a page fault report when doing fault injection test:

BUG: unable to handle page fault for address: fffffffffffffff4
...
RIP: 0010:sysfs_remove_groups+0x25/0x60
...
Call Trace:
msi_destroy_sysfs+0x30/0xa0
free_msi_irqs+0x11d/0x1b0
__pci_enable_msix_range+0x67f/0x760
pci_alloc_irq_vectors_affinity+0xe7/0x170
vp_find_vqs_msix+0x129/0x560
vp_find_vqs+0x52/0x230
vp_modern_find_vqs+0x47/0xb0
p9_virtio_probe+0xa1/0x460 [9pnet_virtio]
...
entry_SYSCALL_64_after_hwframe+0x44/0xae

When populating msi_irqs sysfs failed in msi_capability_init() or
msix_capability_init(), dev->msi_irq_groups will point to ERR_PTR(...).
This will cause a page fault when destroying the wrong
dev->msi_irq_groups in free_msi_irqs().

Define a temp variable and assign it to dev->msi_irq_groups if
the temp variable is not PTR_ERR.

Fixes: 2f170814bdd2 ("genirq/msi: Move MSI sysfs handling from PCI to MSI core")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wang Hai <wanghai38@huawei.com>
Acked-by: Barry Song <song.bao.hua@hisilicon.com>
---
v1->v2: introduce temporary variable 'groups'
drivers/pci/msi.c | 18 ++++++++++++------
1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 0099a00af361..4b4792940e86 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -535,6 +535,7 @@ static int msi_verify_entries(struct pci_dev *dev)
static int msi_capability_init(struct pci_dev *dev, int nvec,
struct irq_affinity *affd)
{
+ const struct attribute_group **groups;
struct msi_desc *entry;
int ret;

@@ -558,12 +559,14 @@ static int msi_capability_init(struct pci_dev *dev, int nvec,
if (ret)
goto err;

- dev->msi_irq_groups = msi_populate_sysfs(&dev->dev);
- if (IS_ERR(dev->msi_irq_groups)) {
- ret = PTR_ERR(dev->msi_irq_groups);
+ groups = msi_populate_sysfs(&dev->dev);
+ if (IS_ERR(groups)) {
+ ret = PTR_ERR(groups);
goto err;
}

+ dev->msi_irq_groups = groups;
+
/* Set MSI enabled bits */
pci_intx_for_msi(dev, 0);
pci_msi_set_enable(dev, 1);
@@ -691,6 +694,7 @@ static void msix_mask_all(void __iomem *base, int tsize)
static int msix_capability_init(struct pci_dev *dev, struct msix_entry *entries,
int nvec, struct irq_affinity *affd)
{
+ const struct attribute_group **groups;
void __iomem *base;
int ret, tsize;
u16 control;
@@ -730,12 +734,14 @@ static int msix_capability_init(struct pci_dev *dev, struct msix_entry *entries,

msix_update_entries(dev, entries);

- dev->msi_irq_groups = msi_populate_sysfs(&dev->dev);
- if (IS_ERR(dev->msi_irq_groups)) {
- ret = PTR_ERR(dev->msi_irq_groups);
+ groups = msi_populate_sysfs(&dev->dev);
+ if (IS_ERR(groups)) {
+ ret = PTR_ERR(groups);
goto out_free;
}

+ dev->msi_irq_groups = groups;
+
/* Set MSI-X enabled bits and unmask the function */
pci_intx_for_msi(dev, 0);
dev->msix_enabled = 1;
--
2.17.1
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