Messages in this thread Patch in this message | | | From | Wentao_Liang <> | Subject | [PATCH] Fix a use-after-free bug | Date | Tue, 14 Jun 2022 09:28:53 +0800 |
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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.
/***********************report begin***************************/
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 ... [ 182.070606] ================================================================== [ 182.071374] Disabling lock debugging due to kernel taint
/************************report 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.
/************************report begin*************************/
root@kernel:~# echo 1 > /sys/bus/pci/devices/0000:00:03.0/remove root@kernel:~#
/************************report end***************************/
Signed-off-by: Wentao_Liang <Wentao_Liang_g@163.com> --- drivers/net/ethernet/neterion/vxge/vxge-main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/neterion/vxge/vxge-main.c b/drivers/net/ethernet/neterion/vxge/vxge-main.c index fa5d4ddf429b..092fd0ae5831 100644 --- a/drivers/net/ethernet/neterion/vxge/vxge-main.c +++ b/drivers/net/ethernet/neterion/vxge/vxge-main.c @@ -4736,10 +4736,10 @@ static void vxge_remove(struct pci_dev *pdev) for (i = 0; i < vdev->no_of_vpath; i++) vxge_free_mac_add_list(&vdev->vpaths[i]); + iounmap(vdev->bar0); vxge_device_unregister(hldev); /* Do not call pci_disable_sriov here, as it will break child devices */ vxge_hw_device_terminate(hldev); - iounmap(vdev->bar0); pci_release_region(pdev, 0); pci_disable_device(pdev); driver_config->config_dev_cnt--; -- 2.25.1
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