> On Mar 1, 2022, at 11:12 PM, Yonghong Song <yhs@xxxxxx> wrote:
>
>
>
> On 3/1/22 4:43 PM, Song Liu wrote:
>> On do_jit failure path, the header is freed by bpf_jit_binary_pack_free.
>> While bpf_jit_binary_pack_free doesn't require proper ro_header->size,
>> bpf_prog_pack_free still uses it. Set header->size in bpf_int_jit_compile
>> before calling bpf_jit_binary_pack_free.
>> Fixes: 1022a5498f6f ("bpf, x86_64: Use bpf_jit_binary_pack_alloc")
>> Fixes: 33c9805860e5 ("bpf: Introduce bpf_jit_binary_pack_[alloc|finalize|free]")
>> Reported-by: Kui-Feng Lee <kuifeng@xxxxxx>
>> Signed-off-by: Song Liu <song@xxxxxxxxxx>
>
> LGTM with a nit below related to comments.
>
> Acked-by: Yonghong Song <yhs@xxxxxx>
>
>> ---
>> arch/x86/net/bpf_jit_comp.c | 6 +++++-
>> kernel/bpf/core.c | 7 ++++---
>> 2 files changed, 9 insertions(+), 4 deletions(-)
>> diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
>> index c7db0fe4de2f..b923d81ff6f9 100644
>> --- a/arch/x86/net/bpf_jit_comp.c
>> +++ b/arch/x86/net/bpf_jit_comp.c
>> @@ -2330,8 +2330,12 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
>> if (proglen <= 0) {
>> out_image:
>> image = NULL;
>> - if (header)
>> + if (header) {
>> + /* set header->size for bpf_arch_text_copy */
>
> This comment is confusing. Setting header->size is not for bpf_arch_text_copy. Probably you mean 'by bpf_arch_text_copy?
> I think this comment is not necessary.
I meant to say set header->size for bpf_jit_binary_pack_free(). I guess it is
not really necessary. Let me remove it.
>
>> + bpf_arch_text_copy(&header->size, &rw_header->size,
>> + sizeof(rw_header->size));
>> bpf_jit_binary_pack_free(header, rw_header);
>> + }
>> prog = orig_prog;
>> goto out_addrs;
>> }
>> diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
>> index ebb0193d07f0..da587e4619e0 100644
>> --- a/kernel/bpf/core.c
>> +++ b/kernel/bpf/core.c
>> @@ -1112,13 +1112,14 @@ int bpf_jit_binary_pack_finalize(struct bpf_prog *prog,
>> * 1) when the program is freed after;
>> * 2) when the JIT engine fails (before bpf_jit_binary_pack_finalize).
>> * For case 2), we need to free both the RO memory and the RW buffer.
>> - * Also, ro_header->size in 2) is not properly set yet, so rw_header->size
>> - * is used for uncharge.
>> + *
>> + * If bpf_jit_binary_pack_free is called before _finalize (jit error),
>
> Do you mean bpf_jit_binary_pack_free() is called before calling
> bpf_jit_binary_pack_finalize()? This seems not the case.
Now I see this is a little confusing. Let me rephrase it in v2.
Thanks,
Song
>
>> + * it is necessary to set ro_header->size properly before freeing it.
>> */
>> void bpf_jit_binary_pack_free(struct bpf_binary_header *ro_header,
>> struct bpf_binary_header *rw_header)
>> {
>> - u32 size = rw_header ? rw_header->size : ro_header->size;
>> + u32 size = ro_header->size;
>> bpf_prog_pack_free(ro_header);
>> kvfree(rw_header);
