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Subject[PATCH AUTOSEL 4.19 37/53] virtio_pci: fix a NULL pointer reference in vp_del_vqs
Date
From: Longpeng <longpeng2@huawei.com>

[ Upstream commit 6a8aae68c87349dbbcd46eac380bc43cdb98a13b ]

If the msix_affinity_masks is alloced failed, then we'll
try to free some resources in vp_free_vectors() that may
access it directly.

We met the following stack in our production:
[ 29.296767] BUG: unable to handle kernel NULL pointer dereference at (null)
[ 29.311151] IP: [<ffffffffc04fe35a>] vp_free_vectors+0x6a/0x150 [virtio_pci]
[ 29.324787] PGD 0
[ 29.333224] Oops: 0000 [#1] SMP
[...]
[ 29.425175] RIP: 0010:[<ffffffffc04fe35a>] [<ffffffffc04fe35a>] vp_free_vectors+0x6a/0x150 [virtio_pci]
[ 29.441405] RSP: 0018:ffff9a55c2dcfa10 EFLAGS: 00010206
[ 29.453491] RAX: 0000000000000000 RBX: ffff9a55c322c400 RCX: 0000000000000000
[ 29.467488] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff9a55c322c400
[ 29.481461] RBP: ffff9a55c2dcfa20 R08: 0000000000000000 R09: ffffc1b6806ff020
[ 29.495427] R10: 0000000000000e95 R11: 0000000000aaaaaa R12: 0000000000000000
[ 29.509414] R13: 0000000000010000 R14: ffff9a55bd2d9e98 R15: ffff9a55c322c400
[ 29.523407] FS: 00007fdcba69f8c0(0000) GS:ffff9a55c2840000(0000) knlGS:0000000000000000
[ 29.538472] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 29.551621] CR2: 0000000000000000 CR3: 000000003ce52000 CR4: 00000000003607a0
[ 29.565886] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 29.580055] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 29.594122] Call Trace:
[ 29.603446] [<ffffffffc04fe8a2>] vp_request_msix_vectors+0xe2/0x260 [virtio_pci]
[ 29.618017] [<ffffffffc04fedc5>] vp_try_to_find_vqs+0x95/0x3b0 [virtio_pci]
[ 29.632152] [<ffffffffc04ff117>] vp_find_vqs+0x37/0xb0 [virtio_pci]
[ 29.645582] [<ffffffffc057bf63>] init_vq+0x153/0x260 [virtio_blk]
[ 29.658831] [<ffffffffc057c1e8>] virtblk_probe+0xe8/0x87f [virtio_blk]
[...]

Cc: Gonglei <arei.gonglei@huawei.com>
Signed-off-by: Longpeng <longpeng2@huawei.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Gonglei <arei.gonglei@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/virtio/virtio_pci_common.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
index 465a6f5142cc..45b04bc91f24 100644
--- a/drivers/virtio/virtio_pci_common.c
+++ b/drivers/virtio/virtio_pci_common.c
@@ -255,9 +255,11 @@ void vp_del_vqs(struct virtio_device *vdev)
for (i = 0; i < vp_dev->msix_used_vectors; ++i)
free_irq(pci_irq_vector(vp_dev->pci_dev, i), vp_dev);

- for (i = 0; i < vp_dev->msix_vectors; i++)
- if (vp_dev->msix_affinity_masks[i])
- free_cpumask_var(vp_dev->msix_affinity_masks[i]);
+ if (vp_dev->msix_affinity_masks) {
+ for (i = 0; i < vp_dev->msix_vectors; i++)
+ if (vp_dev->msix_affinity_masks[i])
+ free_cpumask_var(vp_dev->msix_affinity_masks[i]);
+ }

if (vp_dev->msix_enabled) {
/* Disable the vector used for configuration */
--
2.19.1
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