From: Qian Cai <cai@lca.pw>
To: alex.williamson@redhat.com
Cc: cohuck@redhat.com, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, Qian Cai <cai@lca.pw>
Subject: [PATCH -next] vfio/pci: fix a null-ptr-deref in vfio_config_free()
Date: Thu, 21 May 2020 21:18:29 -0400 [thread overview]
Message-ID: <20200522011829.17301-1-cai@lca.pw> (raw)
It is possible vfio_config_init() does not call vfio_cap_len(), and then
vdev->msi_perm == NULL. Later, in vfio_config_free(), it could trigger a
null-ptr-deref.
BUG: kernel NULL pointer dereference, address: 0000000000000000
RIP: 0010:vfio_config_free+0x7a/0xe0 [vfio_pci]
vfio_config_free+0x7a/0xe0:
free_perm_bits at drivers/vfio/pci/vfio_pci_config.c:340
(inlined by) vfio_config_free at drivers/vfio/pci/vfio_pci_config.c:1760
Call Trace:
vfio_pci_release+0x3a4/0x9e0 [vfio_pci]
vfio_device_fops_release+0x50/0x80 [vfio]
__fput+0x200/0x460
____fput+0xe/0x10
task_work_run+0x127/0x1b0
do_exit+0x782/0x10d0
do_group_exit+0xc7/0x1c0
__x64_sys_exit_group+0x2c/0x30
do_syscall_64+0x64/0x350
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Fixes: bea890bdb161 ("vfio/pci: fix memory leaks in alloc_perm_bits()")
Signed-off-by: Qian Cai <cai@lca.pw>
---
drivers/vfio/pci/vfio_pci_config.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/vfio/pci/vfio_pci_config.c b/drivers/vfio/pci/vfio_pci_config.c
index d127a0c50940..8746c943247a 100644
--- a/drivers/vfio/pci/vfio_pci_config.c
+++ b/drivers/vfio/pci/vfio_pci_config.c
@@ -1757,9 +1757,11 @@ void vfio_config_free(struct vfio_pci_device *vdev)
vdev->vconfig = NULL;
kfree(vdev->pci_config_map);
vdev->pci_config_map = NULL;
- free_perm_bits(vdev->msi_perm);
- kfree(vdev->msi_perm);
- vdev->msi_perm = NULL;
+ if (vdev->msi_perm) {
+ free_perm_bits(vdev->msi_perm);
+ kfree(vdev->msi_perm);
+ vdev->msi_perm = NULL;
+ }
}
/*
--
2.17.2 (Apple Git-113)
next reply other threads:[~2020-05-22 1:18 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-22 1:18 Qian Cai [this message]
2020-05-26 16:21 ` [PATCH -next] vfio/pci: fix a null-ptr-deref in vfio_config_free() Alex Williamson
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