linux-kernel - Re: linux-next: manual merge of the modules tree with the tree

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

Message-ID: <CAGXu5j+geKBjof6peRWgyWra3wfhnLUNDfb5nzEppGGzLKwtOg@mail.gmail.com>
Date:	Sun, 21 Oct 2012 19:09:32 -0700
From:	Kees Cook <keescook@...omium.org>
To:	Stephen Rothwell <sfr@...b.auug.org.au>
Cc:	Rusty Russell <rusty@...tcorp.com.au>, linux-next@...r.kernel.org,
	linux-kernel@...r.kernel.org, David Howells <dhowells@...hat.com>,
	Linus <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: linux-next: manual merge of the modules tree with the tree

On Sun, Oct 21, 2012 at 6:35 PM, Stephen Rothwell <sfr@...b.auug.org.au> wrote:
> Hi Rusty,
>
> Today's linux-next merge of the modules tree got a conflict in
> kernel/module.c between commit caabe240574a ("MODSIGN: Move the magic
> string to the end of a module and eliminate the search") from Linus' tree
> and commit 0250abdeec54 ("module: add syscall to load module from fd")
> from the modules tree.
>
> I fixed it up (I think - see below) and can carry the fix as necessary
> (no action is required).
>
> I do wonder why the above change in Linus' tree seems to have bypassed
> the modules maintainer.
>
> --
> Cheers,
> Stephen Rothwell                    sfr@...b.auug.org.au
>
> diff --cc kernel/module.c
> index 6085f5e,261bf82..0000000
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@@ -2420,18 -2422,27 +2422,18 @@@ static inline void kmemleak_load_module
>   #endif
>
>   #ifdef CONFIG_MODULE_SIG
> - static int module_sig_check(struct load_info *info,
> -                           const void *mod, unsigned long *_len)
> + static int module_sig_check(struct load_info *info)
>   {
>         int err = -ENOKEY;
> -       unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1;
> -       unsigned long len = *_len;
> +       const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1;
> +       const void *mod = info->hdr;

I got rid of "mod" when I did my merge of these changes against
Linus's tree, but I had to cast it in the memcmp, so probably best to
just keep "mod".

>  -      const void *p = mod, *end = mod + info->len;
> ++      unsigned long len = info->len;
>
>  -      /* Poor man's memmem. */
>  -      while ((p = memchr(p, MODULE_SIG_STRING[0], end - p))) {
>  -              if (p + markerlen > end)
>  -                      break;
>  -
>  -              if (memcmp(p, MODULE_SIG_STRING, markerlen) == 0) {
>  -                      const void *sig = p + markerlen;
>  -                      /* Truncate module up to signature. */
>  -                      info->len = p - mod;
>  -                      err = mod_verify_sig(mod, info->len,
>  -                                           sig, end - sig);
>  -                      break;
>  -              }
>  -              p++;
>  +      if (len > markerlen &&
>  +          memcmp(mod + len - markerlen, MODULE_SIG_STRING, markerlen) == 0) {
>  +              /* We truncate the module to discard the signature */
> -               *_len -= markerlen;
> -               err = mod_verify_sig(mod, _len);
> ++              info->len -= markerlen;
> ++              err = mod_verify_sig(mod, &info->len);
>         }
>
>         if (!err) {

-Kees

-- 
Kees Cook
Chrome OS Security
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/