Eduard Zingerman wrote:
>
> On Fri, 2024-08-30 at 11:03 +0900, Jeongjun Park wrote:
>
> [...]
>
> > > diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
> > > index edad152cee8e..d583d76fcace 100644
> > > --- a/kernel/bpf/btf.c
> > > +++ b/kernel/bpf/btf.c
> > > @@ -820,7 +820,6 @@ static bool btf_name_valid_section(const struct btf *btf, u32 offset)
> > >
> > > /* set a limit on identifier length */
> > > src_limit = src + KSYM_NAME_LEN;
> > > - src++;
> > > while (*src && src < src_limit) {
> > > if (!isprint(*src))
> > > return false;
> >
> > However, this patch is logically flawed.
> > It will return true for invalid names with
> > length 1 and src[0] being NULL. So I think
> > it's better to stick with the original patch.
>
> Fair enough, however the isprint check should be done for the first character.
> So the full fix is a combination :)
So does that mean it's appropriate to add if(!isprint(*src)) instead
of if(!*src)?
As far as I know, the first character of name doesn't need isprint() check,
so if that's true, it would be appropriate to use isprint. Once this
is confirmed,
I'll send you a v2 patch that added selftest.
Regards,
Jeongjun Park
>
> --- a/kernel/bpf/btf.c
> +++ b/kernel/bpf/btf.c
> @@ -818,9 +818,11 @@ static bool btf_name_valid_section(const struct btf *btf, u32 offset)
> const char *src = btf_str_by_offset(btf, offset);
> const char *src_limit;
>
> + if (!*src)
> + return false;
> +
> /* set a limit on identifier length */
> src_limit = src + KSYM_NAME_LEN;
> - src++;
> while (*src && src < src_limit) {
> if (!isprint(*src))
> return false;
>
>
> And corresponding test cases (tools/testing/selftests/bpf/prog_tests/btf.c):
>
> {
> .descr = "datasec: name with non-printable first char not is ok",
> .raw_types = {
> /* int */
> BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
> /* VAR x */ /* [2] */
> BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_VAR, 0, 0), 1),
> BTF_VAR_STATIC,
> /* DATASEC ?.data */ /* [3] */
> BTF_TYPE_ENC(3, BTF_INFO_ENC(BTF_KIND_DATASEC, 0, 1), 4),
> BTF_VAR_SECINFO_ENC(2, 0, 4),
> BTF_END_RAW,
> },
> BTF_STR_SEC("\0x\0\7foo"),
> .err_str = "Invalid name",
> .btf_load_err = true,
> },{
> .descr = "datasec: name '\\0' is not ok",
> .raw_types = {
> /* int */
> BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
> /* VAR x */ /* [2] */
> BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_VAR, 0, 0), 1),
> BTF_VAR_STATIC,
> /* DATASEC \0 */ /* [3] */
> BTF_TYPE_ENC(3, BTF_INFO_ENC(BTF_KIND_DATASEC, 0, 1), 4),
> BTF_VAR_SECINFO_ENC(2, 0, 4),
> BTF_END_RAW,
> },
> BTF_STR_SEC("\0x\0"),
> .err_str = "Invalid name",
> .btf_load_err = true,
> },
>
> Could you please resend your patch as a patch-set fix + selftests update?
>
