CVE-2022-50168

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

bpf, x86: fix freeing of not-finalized bpf_prog_pack

syzbot reported a few issues with bpf_prog_pack [1], [2]. This only happens

with multiple subprogs. In jit_subprogs(), we first call bpf_int_jit_compile()

on each sub program. And then, we call it on each sub program again. jit_data

is not freed in the first call of bpf_int_jit_compile(). Similarly we don't

call bpf_jit_binary_pack_finalize() in the first call of bpf_int_jit_compile().

If bpf_int_jit_compile() failed for one sub program, we will call

bpf_jit_binary_pack_finalize() for this sub program. However, we don't have a

chance to call it for other sub programs. Then we will hit "goto out_free" in

jit_subprogs(), and call bpf_jit_free on some subprograms that haven't got

bpf_jit_binary_pack_finalize() yet.

At this point, bpf_jit_binary_pack_free() is called and the whole 2MB page is

freed erroneously.

Fix this with a custom bpf_jit_free() for x86_64, which calls

bpf_jit_binary_pack_finalize() if necessary. Also, with custom

bpf_jit_free(), bpf_prog_aux->use_bpf_prog_pack is not needed any more,

remove it.

[1] https://syzkaller.appspot.com/bug?extid=2f649ec6d2eea1495a8f

[2] https://syzkaller.appspot.com/bug?extid=87f65c75f4a72db05445