linux-kernel - Re: [PATCH] pstore/platform: build fix when crypto API are disabled

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Date:   Tue, 7 Jul 2020 13:25:02 +0200
From:   Matteo Croce <mcroce@...ux.microsoft.com>
To:     Kees Cook <keescook@...omium.org>
Cc:     Anton Vorontsov <anton@...msg.org>,
        Colin Cross <ccross@...roid.com>,
        Tony Luck <tony.luck@...el.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] pstore/platform: build fix when crypto API are disabled

On Tue, Jul 7, 2020 at 4:37 AM Kees Cook <keescook@...omium.org> wrote:
>
> On Tue, Jul 07, 2020 at 01:40:45AM +0200, Matteo Croce wrote:
> > From: Matteo Croce <mcroce@...rosoft.com>
> >
> > When building a kernel with CONFIG_PSTORE=y and CONFIG_CRYPTO not set,
> > a build error happens:
> >
> >     ld: fs/pstore/platform.o: in function `pstore_dump':
> >     platform.c:(.text+0x3f9): undefined reference to `crypto_comp_compress'
> >     ld: fs/pstore/platform.o: in function `pstore_get_backend_records':
> >     platform.c:(.text+0x784): undefined reference to `crypto_comp_decompress'
> >
> > This because some pstore code uses crypto_comp_(de)compress
> > regardless of the CONFIG_CRYPTO status.
> > Fix it by wrapping the (de)compress usage by IS_ENABLED(CONFIG_PSTORE_COMPRESS)
>
> I'm surprised this hasn't come up before in a randconfig! But I guess
> it'd require a very lucky config: picking CONFIG_PSTORE but not
> CONFIG_CRYPTO _and_ 0 of the many compression options in pstore. :P
>
> But yes, I can reproduce this with:
>
> # CONFIG_CRYPTO is not set
> CONFIG_PSTORE=y
> # CONFIG_PSTORE_DEFLATE_COMPRESS is not set
> # CONFIG_PSTORE_LZO_COMPRESS is not set
> # CONFIG_PSTORE_LZ4_COMPRESS is not set
> # CONFIG_PSTORE_LZ4HC_COMPRESS is not set
> # CONFIG_PSTORE_842_COMPRESS is not set
> # CONFIG_PSTORE_ZSTD_COMPRESS is not set
>
> >
> > Signed-off-by: Matteo Croce <mcroce@...rosoft.com>
> > ---
> >  fs/pstore/platform.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
> > index a9e297eefdff..6022d8359f96 100644
> > --- a/fs/pstore/platform.c
> > +++ b/fs/pstore/platform.c
> > @@ -436,7 +436,7 @@ static void pstore_dump(struct kmsg_dumper *dumper,
> >                                         dst_size, &dump_size))
> >                       break;
> >
> > -             if (big_oops_buf) {
> > +             if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && big_oops_buf) {
> >                       zipped_len = pstore_compress(dst, psinfo->buf,
> >                                               header_size + dump_size,
> >                                               psinfo->bufsize);
> > @@ -668,7 +668,7 @@ static void decompress_record(struct pstore_record *record)
> >       int unzipped_len;
> >       char *unzipped, *workspace;
> >
> > -     if (!record->compressed)
> > +     if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !record->compressed)
> >               return;
> >
> >       /* Only PSTORE_TYPE_DMESG support compression. */
> > --
> > 2.26.2
>
> This report also reminds me that I want to stop hard-coding the possible
> compressors[1].
>
> Regardless, for now, I'd like a slightly different patch, which pokes
> pstore_compress() instead of doing it inline in pstore_dump():
>
>
> diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
> index a9e297eefdff..36714df37d5d 100644
> --- a/fs/pstore/platform.c
> +++ b/fs/pstore/platform.c
> @@ -269,6 +269,9 @@ static int pstore_compress(const void *in, void *out,
>  {
>         int ret;
>
> +       if (!IS_ENABLED(CONFIG_PSTORE_COMPRESSION))
> +               return -EINVAL;
> +
>         ret = crypto_comp_compress(tfm, in, inlen, out, &outlen);
>         if (ret) {
>                 pr_err("crypto_comp_compress failed, ret = %d!\n", ret);
> @@ -668,7 +671,7 @@ static void decompress_record(struct pstore_record *record)
>         int unzipped_len;
>         char *unzipped, *workspace;
>
> -       if (!record->compressed)
> +       if (!IS_ENABLED(CONFIG_PSTORE_COMPRESSION) || !record->compressed)
>                 return;
>
>         /* Only PSTORE_TYPE_DMESG support compression. */
>
>
>
> Let me know if that works for you (it fixes it on my end).
>

Yes, it works for me!

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