8fc74d1863
The pointer vdev points to a memory region adjacent to a net_device
structure ndev, which is a field of hldev. At line 4740, the invocation
to vxge_device_unregister unregisters device hldev, and it also releases
the memory region pointed by vdev->bar0. At line 4743, the freed memory
region is referenced (i.e., iounmap(vdev->bar0)), resulting in a
use-after-free vulnerability. We can fix the bug by calling iounmap
before vxge_device_unregister.
4721. static void vxge_remove(struct pci_dev *pdev)
4722. {
4723. struct __vxge_hw_device *hldev;
4724. struct vxgedev *vdev;
…
4731. vdev = netdev_priv(hldev->ndev);
…
4740. vxge_device_unregister(hldev);
4741. /* Do not call pci_disable_sriov here, as it
will break child devices */
4742. vxge_hw_device_terminate(hldev);
4743. iounmap(vdev->bar0);
…
4749 vxge_debug_init(vdev->level_trace, "%s:%d
Device unregistered",
4750 __func__, __LINE__);
4751 vxge_debug_entryexit(vdev->level_trace, "%s:%d
Exiting...", __func__,
4752 __LINE__);
4753. }
This is the screenshot when the vulnerability is triggered by using
KASAN. We can see that there is a use-after-free reported by KASAN.
/***************************start**************************/
root@kernel:~# echo 1 > /sys/bus/pci/devices/0000:00:03.0/remove
[ 178.296316] vxge_remove
[ 182.057081]
==================================================================
[ 182.057548] BUG: KASAN: use-after-free in vxge_remove+0xe0/0x15c
[ 182.057760] Read of size 8 at addr ffff888006c76598 by task bash/119
[ 182.057983]
[ 182.058747] CPU: 0 PID: 119 Comm: bash Not tainted 5.18.0 #5
[ 182.058919] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
[ 182.059463] Call Trace:
[ 182.059726] <TASK>
[ 182.060017] dump_stack_lvl+0x34/0x44
[ 182.060316] print_report.cold+0xb2/0x6b7
[ 182.060401] ? kfree+0x89/0x290
[ 182.060478] ? vxge_remove+0xe0/0x15c
[ 182.060545] kasan_report+0xa9/0x120
[ 182.060629] ? vxge_remove+0xe0/0x15c
[ 182.060706] vxge_remove+0xe0/0x15c
[ 182.060793] pci_device_remove+0x5d/0xe0
[ 182.060968] device_release_driver_internal+0xf1/0x180
[ 182.061063] pci_stop_bus_device+0xae/0xe0
[ 182.061150] pci_stop_and_remove_bus_device_locked+0x11/0x20
[ 182.061236] remove_store+0xc6/0xe0
[ 182.061297] ? subordinate_bus_number_show+0xc0/0xc0
[ 182.061359] ? __mutex_lock_slowpath+0x10/0x10
[ 182.061438] ? sysfs_kf_write+0x6d/0xa0
[ 182.061525] kernfs_fop_write_iter+0x1b0/0x260
[ 182.061610] ? sysfs_kf_bin_read+0xf0/0xf0
[ 182.061695] new_sync_write+0x209/0x310
[ 182.061789] ? new_sync_read+0x310/0x310
[ 182.061865] ? cgroup_rstat_updated+0x5c/0x170
[ 182.061937] ? preempt_count_sub+0xf/0xb0
[ 182.061995] ? pick_next_entity+0x13a/0x220
[ 182.062063] ? __inode_security_revalidate+0x44/0x80
[ 182.062155] ? security_file_permission+0x46/0x2a0
[ 182.062230] vfs_write+0x33f/0x3e0
[ 182.062303] ksys_write+0xb4/0x150
[ 182.062369] ? __ia32_sys_read+0x40/0x40
[ 182.062451] do_syscall_64+0x3b/0x90
[ 182.062531] entry_SYSCALL_64_after_hwframe+0x46/0xb0
[ 182.062894] RIP: 0033:0x7f3f37d17274
[ 182.063558] Code: 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b3 0f 1f
80 00 00 00 00 48 8d 05 89 54 0d 00 8b 00 85 c0 75 13 b8 01 00 00 00 0f
05 <48> 3d 00 f0 ff ff 77 54 c3 0f 1f 00 41 54 49 89 d4 55 48 89 f5 53
[ 182.063797] RSP: 002b:00007ffd5ba9e178 EFLAGS: 00000246
ORIG_RAX: 0000000000000001
[ 182.064117] RAX: ffffffffffffffda RBX: 0000000000000002
RCX: 00007f3f37d17274
[ 182.064219] RDX: 0000000000000002 RSI: 000055bbec327180
RDI: 0000000000000001
[ 182.064315] RBP: 000055bbec327180 R08: 000000000000000a
R09: 00007f3f37de7cf0
[ 182.064414] R10: 000000000000000a R11: 0000000000000246
R12: 00007f3f37de8760
[ 182.064513] R13: 0000000000000002 R14: 00007f3f37de3760
R15: 0000000000000002
[ 182.064691] </TASK>
[ 182.064916]
[ 182.065224] The buggy address belongs to the physical page:
[ 182.065804] page:00000000ef31e4f4 refcount:0 mapcount:0
mapping:0000000000000000 index:0x0 pfn:0x6c76
[ 182.067419] flags: 0x100000000000000(node=0|zone=1)
[ 182.068997] raw: 0100000000000000 0000000000000000
ffffea00001b1d88 0000000000000000
[ 182.069118] raw: 0000000000000000 0000000000000000
00000000ffffffff 0000000000000000
[ 182.069294] page dumped because: kasan: bad access detected
[ 182.069331]
[ 182.069360] Memory state around the buggy address:
[ 182.070006] ffff888006c76480: ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff
[ 182.070136] ffff888006c76500: ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff
[ 182.070230] >ffff888006c76580: ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff
[ 182.070305] ^
[ 182.070456] ffff888006c76600: ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff
[ 182.070505] ffff888006c76680: ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff
[ 182.070606]
==================================================================
[ 182.071374] Disabling lock debugging due to kernel taint
/*****************************end*****************************/
After fixing the bug as done in the patch, we can find KASAN do not report
the bug and the device(00:03.0) has been successfully removed.
/*****************************start***************************/
root@kernel:~# echo 1 > /sys/bus/pci/devices/0000:00:03.0/remove
root@kernel:~#
/******************************end****************************/
Signed-off-by: Wentao_Liang <Wentao_Liang_g@163.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.