diff options
| author | Song Liu <song@kernel.org> | 2022-07-06 03:26:12 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-08-17 16:14:48 +0300 |
| commit | 60e66074812dde9cde3d99cdd3caa9e40f1a4516 (patch) | |
| tree | 15e010fed531e0e389c410b4a2a0c4239be7bf56 /arch/x86 | |
| parent | 7018bd9fac6237e706d175d0a5926de9226c664a (diff) | |
| download | linux-60e66074812dde9cde3d99cdd3caa9e40f1a4516.tar.xz | |
bpf, x86: fix freeing of not-finalized bpf_prog_pack
[ Upstream commit 1d5f82d9dd477d5c66e0214a68c3e4f308eadd6d ]
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.
Fixes: 1022a5498f6f ("bpf, x86_64: Use bpf_jit_binary_pack_alloc")
[1] https://syzkaller.appspot.com/bug?extid=2f649ec6d2eea1495a8f
[2] https://syzkaller.appspot.com/bug?extid=87f65c75f4a72db05445
Reported-by: syzbot+2f649ec6d2eea1495a8f@syzkaller.appspotmail.com
Reported-by: syzbot+87f65c75f4a72db05445@syzkaller.appspotmail.com
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20220706002612.4013790-1-song@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/net/bpf_jit_comp.c | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index eba704b9ce1e..41d170653e8d 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -2512,3 +2512,28 @@ bool bpf_jit_supports_subprog_tailcalls(void) { return true; } + +void bpf_jit_free(struct bpf_prog *prog) +{ + if (prog->jited) { + struct x64_jit_data *jit_data = prog->aux->jit_data; + struct bpf_binary_header *hdr; + + /* + * If we fail the final pass of JIT (from jit_subprogs), + * the program may not be finalized yet. Call finalize here + * before freeing it. + */ + if (jit_data) { + bpf_jit_binary_pack_finalize(prog, jit_data->header, + jit_data->rw_header); + kvfree(jit_data->addrs); + kfree(jit_data); + } + hdr = bpf_jit_binary_pack_hdr(prog); + bpf_jit_binary_pack_free(hdr, NULL); + WARN_ON_ONCE(!bpf_prog_kallsyms_verify_off(prog)); + } + + bpf_prog_unlock_free(prog); +} |