linux-kernel - [PATCH] PCI/MSI: fix page fault when msi_populate

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Date:   Mon, 11 Oct 2021 16:40:49 +0800
From:   Wang Hai <wanghai38@...wei.com>
To:     <bhelgaas@...gle.com>, <maz@...nel.org>, <tglx@...utronix.de>,
        <song.bao.hua@...ilicon.com>, <gregkh@...uxfoundation.org>
CC:     <linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] PCI/MSI: fix page fault when msi_populate_sysfs() failed

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]
 virtio_dev_probe+0x1ed/0x2e0
 really_probe+0x1c7/0x400
 __driver_probe_device+0xa4/0x120
 driver_probe_device+0x32/0xe0
 __driver_attach+0xbf/0x130
 bus_for_each_dev+0xbb/0x110
 driver_attach+0x27/0x30
 bus_add_driver+0x1d9/0x270
 driver_register+0xa9/0x180
 register_virtio_driver+0x31/0x50
 p9_virtio_init+0x3c/0x1000 [9pnet_virtio]
 do_one_initcall+0x7b/0x380
 do_init_module+0x5f/0x21e
 load_module+0x265c/0x2c60
 __do_sys_finit_module+0xb0/0xf0
 __x64_sys_finit_module+0x1a/0x20
 do_syscall_64+0x34/0xb0
 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().

Fix this by setting dev->msi_irq_groups to NULL when msi_populate_sysfs()
failed.

Fixes: 2f170814bdd2 ("genirq/msi: Move MSI sysfs handling from PCI to MSI core")
Reported-by: Hulk Robot <hulkci@...wei.com>
Signed-off-by: Wang Hai <wanghai38@...wei.com>
---
 drivers/pci/msi.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 0099a00af361..6f75db9f3be7 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -561,6 +561,7 @@ static int msi_capability_init(struct pci_dev *dev, int nvec,
 	dev->msi_irq_groups = msi_populate_sysfs(&dev->dev);
 	if (IS_ERR(dev->msi_irq_groups)) {
 		ret = PTR_ERR(dev->msi_irq_groups);
+		dev->msi_irq_groups = NULL;
 		goto err;
 	}

@@ -733,6 +734,7 @@ static int msix_capability_init(struct pci_dev *dev, struct msix_entry *entries,
 	dev->msi_irq_groups = msi_populate_sysfs(&dev->dev);
 	if (IS_ERR(dev->msi_irq_groups)) {
 		ret = PTR_ERR(dev->msi_irq_groups);
+		dev->msi_irq_groups = NULL;
 		goto out_free;
 	}

-- 
2.17.1