CVE-2021-47589

In the Linux kernel, the following vulnerability has been resolved:

igbvf: fix double free in igbvf_probe

In igbvf_probe, if register_netdev() fails, the program will go to label err_hw_init, and then to label err_ioremap. In free_netdev() which is just below label err_ioremap, there is list_for_each_entry_safe and netif_napi_del which aims to delete all entries in dev->napi_list. The program has added an entry adapter->rx_ring->napi which is added by netif_napi_add in igbvf_alloc_queues(). However, adapter->rx_ring has been freed below label err_hw_init. So this a UAF.

In terms of how to patch the problem, we can refer to igbvf_remove() and delete the entry before adapter->rx_ring.

The KASAN logs are as follows:

[ 35.126075] BUG: KASAN: use-after-free in free_netdev+0x1fd/0x450 [ 35.127170] Read of size 8 at addr ffff88810126d990 by task modprobe/366 [ 35.128360] [ 35.128643] CPU: 1 PID: 366 Comm: modprobe Not tainted 5.15.0-rc2+ #14 [ 35.129789] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014 [ 35.131749] Call Trace: [ 35.132199] dump_stack_lvl+0x59/0x7b [ 35.132865] print_address_description+0x7c/0x3b0 [ 35.133707] ? free_netdev+0x1fd/0x450 [ 35.134378] __kasan_report+0x160/0x1c0 [ 35.135063] ? free_netdev+0x1fd/0x450 [ 35.135738] kasan_report+0x4b/0x70 [ 35.136367] free_netdev+0x1fd/0x450 [ 35.137006] igbvf_probe+0x121d/0x1a10 [igbvf] [ 35.137808] ? igbvf_vlan_rx_add_vid+0x100/0x100 [igbvf] [ 35.138751] local_pci_probe+0x13c/0x1f0 [ 35.139461] pci_device_probe+0x37e/0x6c0 [ 35.165526] [ 35.165806] Allocated by task 366: [ 35.166414] ____kasan_kmalloc+0xc4/0xf0 [ 35.167117] foo_kmem_cache_alloc_trace+0x3c/0x50 [igbvf] [ 35.168078] igbvf_probe+0x9c5/0x1a10 [igbvf] [ 35.168866] local_pci_probe+0x13c/0x1f0 [ 35.169565] pci_device_probe+0x37e/0x6c0 [ 35.179713] [ 35.179993] Freed by task 366: [ 35.180539] kasan_set_track+0x4c/0x80 [ 35.181211] kasan_set_free_info+0x1f/0x40 [ 35.181942] ____kasan_slab_free+0x103/0x140 [ 35.182703] kfree+0xe3/0x250 [ 35.183239] igbvf_probe+0x1173/0x1a10 [igbvf] [ 35.184040] local_pci_probe+0x13c/0x1f0

Weakness

The product calls free() twice on the same memory address, potentially leading to modification of unexpected memory locations.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/74a16e062b23332d8db017ff4a41e16279c44411
• https://git.kernel.org/stable/c/79d9b092035dcdbe636b70433149df9cc6db1e49
• https://git.kernel.org/stable/c/8addba6cab94ce01686ea2e80ed1530f9dc33a9a
• https://git.kernel.org/stable/c/8d0c927a9fb2b4065230936b77b54f857a3754fc
• https://git.kernel.org/stable/c/944b8be08131f5faf2cd2440aa1c24a39a163a54
• https://git.kernel.org/stable/c/b6d335a60dc624c0d279333b22c737faa765b028
• https://git.kernel.org/stable/c/cc9b655bb84f1be283293dfea94dff9a31b106ac
• https://git.kernel.org/stable/c/ffe1695b678729edec04037e691007900a2b2beb