In the Linux kernel, the following vulnerability has been resolved:
vxlan: Fix nexthop hash size
The nexthop code expects a 31 bit hash, such as what is returned by fib_multipath_hash() and rt6_multipath_hash(). Passing the 32 bit hash returned by skb_get_hash() can lead to problems related to the fact that 'int hash' is a negative number when the MSB is set.
In the case of hash threshold nexthop groups, nexthop_select_path_hthr() will disproportionately select the first nexthop group entry. In the case of resilient nexthop groups, nexthop_select_path_res() may do an out of bounds access in nh_buckets[], for example: hash = -912054133 num_nh_buckets = 2 bucket_index = 65535
which leads to the following panic:
BUG: unable to handle page fault for address: ffffc900025910c8 PGD 100000067 P4D 100000067 PUD 10026b067 PMD 0 Oops: 0002 [#1] PREEMPT SMP KASAN NOPTI CPU: 4 PID: 856 Comm: kworker/4:3 Not tainted 6.5.0-rc2+ #34 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 Workqueue: ipv6_addrconf addrconf_dad_work RIP: 0010:nexthop_select_path+0x197/0xbf0 Code: c1 e4 05 be 08 00 00 00 4c 8b 35 a4 14 7e 01 4e 8d 6c 25 00 4a 8d 7c 25 08 48 01 dd e8 c2 25 15 ff 49 8d 7d 08 e8 39 13 15 ff <4d> 89 75 08 48 89 ef e8 7d 12 15 ff 48 8b 5d 00 e8 14 55 2f 00 85 RSP: 0018:ffff88810c36f260 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 00000000002000c0 RCX: ffffffffaf02dd77 RDX: dffffc0000000000 RSI: 0000000000000008 RDI: ffffc900025910c8 RBP: ffffc900025910c0 R08: 0000000000000001 R09: fffff520004b2219 R10: ffffc900025910cf R11: 31392d2068736168 R12: 00000000002000c0 R13: ffffc900025910c0 R14: 00000000fffef608 R15: ffff88811840e900 FS: 0000000000000000(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffc900025910c8 CR3: 0000000129d00000 CR4: 0000000000750ee0 PKRU: 55555554 Call Trace: <TASK> ? __die+0x23/0x70 ? page_fault_oops+0x1ee/0x5c0 ?...