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

bpf: Check the remaining info_cnt before repeating btf fields

When trying to repeat the btf fields for array of nested struct, it
doesn't check the remaining info_cnt. The following splat will be
reported when the value of ret * nelems is greater than BTF_FIELDS_MAX:

------------[ cut here ]------------
UBSAN: array-index-out-of-bounds in ../kernel/bpf/btf.c:3951:49
index 11 is out of range for type 'btf_field_info [11]'
CPU: 6 UID: 0 PID: 411 Comm: test_progs ...... 6.11.0-rc4+ #1
Tainted: [O]=OOT_MODULE
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ...
Call Trace:
<TASK>
dump_stack_lvl+0x57/0x70
dump_stack+0x10/0x20
ubsan_epilogue+0x9/0x40
__ubsan_handle_out_of_bounds+0x6f/0x80
? kallsyms_lookup_name+0x48/0xb0
btf_parse_fields+0x992/0xce0
map_create+0x591/0x770
__sys_bpf+0x229/0x2410
__x64_sys_bpf+0x1f/0x30
x64_sys_call+0x199/0x9f0
do_syscall_64+0x3b/0xc0
entry_SYSCALL_64_after_hwframe+0x4b/0x53
RIP: 0033:0x7fea56f2cc5d
......
</TASK>
---[ end trace ]---

Fix it by checking the remaining info_cnt in btf_repeat_fields() before
repeating the btf fields.