netdev - Re: [PATCH v2 bpf 0/2] Fix BTF verification of enum members with a selftest

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <CAADnVQ+o-TA6WtKk6f5z-T2xO6A6VXhcWCv2uqFA7=EqCh647A@mail.gmail.com>
Date:   Tue, 10 Mar 2020 10:26:04 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Martin KaFai Lau <kafai@...com>
Cc:     Yoshiki Komachi <komachi.yoshiki@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Andrii Nakryiko <andriin@...com>,
        Network Development <netdev@...r.kernel.org>,
        bpf <bpf@...r.kernel.org>
Subject: Re: [PATCH v2 bpf 0/2] Fix BTF verification of enum members with a selftest

On Tue, Mar 10, 2020 at 9:46 AM Martin KaFai Lau <kafai@...com> wrote:
>
> On Tue, Mar 10, 2020 at 04:32:28PM +0900, Yoshiki Komachi wrote:
> > btf_enum_check_member() checked if the size of "enum" as a struct
> > member exceeded struct_size or not. Then, the function compared it
> > with the size of "int". Although the size of "enum" is 4-byte by
> > default (i.e., equivalent to "int"), the packing feature enables
> > us to reduce it, as illustrated by the following example:
> >
> > struct A {
> >         char m;
> >         enum { E0, E1 } __attribute__((packed)) n;
> > };
> >
> > With such a setup above, the bpf loader gave an error attempting
> > to load it:
> >
> > ------------------------------------------------------------------
> > ...
> >
> > [3] ENUM (anon) size=1 vlen=2
> >         E0 val=0
> >         E1 val=1
> > [4] STRUCT A size=2 vlen=2
> >         m type_id=2 bits_offset=0
> >         n type_id=3 bits_offset=8
> >
> > [4] STRUCT A size=2 vlen=2
> >         n type_id=3 bits_offset=8 Member exceeds struct_size
> >
> > libbpf: Error loading .BTF into kernel: -22.
> >
> > ------------------------------------------------------------------
> >
> > The related issue was previously fixed by the commit 9eea98497951 ("bpf:
> > fix BTF verification of enums"). On the other hand, this series fixes
> > this issue as well, and adds a selftest program for it.
> >
> > Changes in v2:
> > - change an example in commit message based on Andrii's review
> > - add a selftest program for packed "enum" type members in struct/union
> Acked-by: Martin KaFai Lau <kafai@...com>

Applied to bpf tree. Thanks