CVE-2022-49695

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

igb: fix a use-after-free issue in igb_clean_tx_ring

Fix the following use-after-free bug in igb_clean_tx_ring routine when the NIC is running in XDP mode. The issue can be triggered redirecting traffic into the igb NIC and then closing the device while the traffic is flowing.

[ 73.322719] CPU: 1 PID: 487 Comm: xdp_redirect Not tainted 5.18.3-apu2 #9 [ 73.330639] Hardware name: PC Engines APU2/APU2, BIOS 4.0.7 02/28/2017 [ 73.337434] RIP: 0010:refcount_warn_saturate+0xa7/0xf0 [ 73.362283] RSP: 0018:ffffc9000081f798 EFLAGS: 00010282 [ 73.367761] RAX: 0000000000000000 RBX: ffffc90000420f80 RCX: 0000000000000000 [ 73.375200] RDX: ffff88811ad22d00 RSI: ffff88811ad171e0 RDI: ffff88811ad171e0 [ 73.382590] RBP: 0000000000000900 R08: ffffffff82298f28 R09: 0000000000000058 [ 73.390008] R10: 0000000000000219 R11: ffffffff82280f40 R12: 0000000000000090 [ 73.397356] R13: ffff888102343a40 R14: ffff88810359e0e4 R15: 0000000000000000 [ 73.404806] FS: 00007ff38d31d740(0000) GS:ffff88811ad00000(0000) knlGS:0000000000000000 [ 73.413129] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 73.419096] CR2: 000055cff35f13f8 CR3: 0000000106391000 CR4: 00000000000406e0 [ 73.426565] Call Trace: [ 73.429087] [ 73.431314] igb_clean_tx_ring+0x43/0x140 [igb] [ 73.436002] igb_down+0x1d7/0x220 [igb] [ 73.439974] __igb_close+0x3c/0x120 [igb] [ 73.444118] igb_xdp+0x10c/0x150 [igb] [ 73.447983] ? igb_pci_sriov_configure+0x70/0x70 [igb] [ 73.453362] dev_xdp_install+0xda/0x110 [ 73.457371] dev_xdp_attach+0x1da/0x550 [ 73.461369] do_setlink+0xfd0/0x10f0 [ 73.465166] ? __nla_validate_parse+0x89/0xc70 [ 73.469714] rtnl_setlink+0x11a/0x1e0 [ 73.473547] rtnetlink_rcv_msg+0x145/0x3d0 [ 73.477709] ? rtnl_calcit.isra.0+0x130/0x130 [ 73.482258] netlink_rcv_skb+0x8d/0x110 [ 73.486229] netlink_unicast+0x230/0x340 [ 73.490317] netlink_sendmsg+0x215/0x470 [ 73.494395] __sys_sendto+0x179/0x190 [ 73.498268] ? move_addr_to_user+0x37/0x70 [ 73.502547] ? __sys_getsockname+0x84/0xe0 [ 73.506853] ? netlink_setsockopt+0x1c1/0x4a0 [ 73.511349] ? __sys_setsockopt+0xc8/0x1d0 [ 73.515636] __x64_sys_sendto+0x20/0x30 [ 73.519603] do_syscall_64+0x3b/0x80 [ 73.523399] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 73.528712] RIP: 0033:0x7ff38d41f20c [ 73.551866] RSP: 002b:00007fff3b945a68 EFLAGS: 00000246 ORIG_RAX: 000000000000002c [ 73.559640] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007ff38d41f20c [ 73.567066] RDX: 0000000000000034 RSI: 00007fff3b945b30 RDI: 0000000000000003 [ 73.574457] RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000 [ 73.581852] R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff3b945ab0 [ 73.589179] R13: 0000000000000000 R14: 0000000000000003 R15: 00007fff3b945b30 [ 73.596545] [ 73.598842] —[ end trace 0000000000000000 ]—

Weakness

Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code.

Affected Software

Extended Description

The use of previously-freed memory can have any number of adverse consequences, ranging from the corruption of valid data to the execution of arbitrary code, depending on the instantiation and timing of the flaw. The simplest way data corruption may occur involves the system’s reuse of the freed memory. Use-after-free errors have two common and sometimes overlapping causes:

In this scenario, the memory in question is allocated to another pointer validly at some point after it has been freed. The original pointer to the freed memory is used again and points to somewhere within the new allocation. As the data is changed, it corrupts the validly used memory; this induces undefined behavior in the process. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.

Potential Mitigations

References

• https://git.kernel.org/stable/c/2af944210dc23d43d8208dafac4df7be7e3c168b
• https://git.kernel.org/stable/c/3f6a57ee8544ec3982f8a3cbcbf4aea7d47eb9ec
• https://git.kernel.org/stable/c/68a0ed06dcd5d3ea732d011c0b83d66e4791f521
• https://git.kernel.org/stable/c/c12a2c9b1b460ed72e6b3c33aac1ef51b0329b66