CVE-2022-49667

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

net: bonding: fix use-after-free after 802.3ad slave unbind

commit 0622cab0341c (bonding: fix 802.3ad aggregator reselection), resolve case, when there is several aggregation groups in the same bond. bond_3ad_unbind_slave will invalidate (clear) aggregator when __agg_active_ports return zero. So, ad_clear_agg can be executed even, when num_of_ports!=0. Than bond_3ad_unbind_slave can be executed again for, previously cleared aggregator. NOTE: at this time bond_3ad_unbind_slave will not update slave ports list, because lag_ports==NULL. So, here we got slave ports, pointing to freed aggregator memory.

Fix with checking actual number of ports in group (as was before commit 0622cab0341c (bonding: fix 802.3ad aggregator reselection) ), before ad_clear_agg().

The KASAN logs are as follows:

[ 767.617392] ================================================================== [ 767.630776] BUG: KASAN: use-after-free in bond_3ad_state_machine_handler+0x13dc/0x1470 [ 767.638764] Read of size 2 at addr ffff00011ba9d430 by task kworker/u8:7/767 [ 767.647361] CPU: 3 PID: 767 Comm: kworker/u8:7 Tainted: G O 5.15.11 #15 [ 767.655329] Hardware name: DNI AmazonGo1 A7040 board (DT) [ 767.660760] Workqueue: lacp_1 bond_3ad_state_machine_handler [ 767.666468] Call trace: [ 767.668930] dump_backtrace+0x0/0x2d0 [ 767.672625] show_stack+0x24/0x30 [ 767.675965] dump_stack_lvl+0x68/0x84 [ 767.679659] print_address_description.constprop.0+0x74/0x2b8 [ 767.685451] kasan_report+0x1f0/0x260 [ 767.689148] __asan_load2+0x94/0xd0 [ 767.692667] bond_3ad_state_machine_handler+0x13dc/0x1470

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/050133e1aa2cb49bb17be847d48a4431598ef562
• https://git.kernel.org/stable/c/2765749def4765c5052a4c66445cf4c96fcccdbc
• https://git.kernel.org/stable/c/63b2fe509f69b90168a75e04e14573dccf7984e6
• https://git.kernel.org/stable/c/893825289ba840afd86bfffcb6f7f363c73efff8
• https://git.kernel.org/stable/c/a853b7a3a9fd1d74a4ccdd9cd73512b7dace2f1e
• https://git.kernel.org/stable/c/b90ac60303063a43e17dd4aec159067599d255e6
• https://git.kernel.org/stable/c/ef0af7d08d26c5333ff4944a559279464edf6f15
• https://git.kernel.org/stable/c/f162f7c348fa2a5555bafdb5cc890b89b221e69c