linux-kernel - Re: [PATCH v2 2/5] modules: Refactor + kdoc elf_validity_cached

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Message-ID: <2023111818-agent-verdict-99a5@gregkh>
Date:   Sat, 18 Nov 2023 06:36:49 -0500
From:   Greg KH <greg@...ah.com>
To:     Matthew Maurer <mmaurer@...gle.com>
Cc:     Masahiro Yamada <masahiroy@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Miguel Ojeda <ojeda@...nel.org>, Gary Guo <gary@...yguo.net>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Nicolas Schier <nicolas@...sle.eu>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        linux-modules@...r.kernel.org, linux-kbuild@...r.kernel.org,
        rust-for-linux@...r.kernel.org, Laura Abbott <laura@...bott.name>
Subject: Re: [PATCH v2 2/5] modules: Refactor + kdoc elf_validity_cached_copy

On Sat, Nov 18, 2023 at 02:54:43AM +0000, Matthew Maurer wrote:
> Functionality is almost identical, just structured for better
> documentation and readability. Changes:
> 
> * Section names are checked for *all* non-SHT_NULL sections, not just
>   SHF_ALLOC sections. We have code that accesses section names of
>   non-SHF_ALLOC sections (see find_any_sec for example)
> * The section name check occurs *before* strcmping on section names.
>   Previously, it was possible to use an out-of-bounds offset to strcmp
>   against ".modinfo" or ".gnu.linkonce.this_module"
> * strtab is checked for NUL lead+termination and nonzero size
> * The symbol table is swept to ensure offsets are inbounds of strtab
> 
> While some of these oversights would normally be worrying, all of the
> potentially unverified accesses occur after signature check, and only in
> response to a user who can load a kernel module.
> 
> Signed-off-by: Matthew Maurer <mmaurer@...gle.com>
> ---
>  kernel/module/internal.h |   7 +-
>  kernel/module/main.c     | 585 +++++++++++++++++++++++++++++----------
>  2 files changed, 444 insertions(+), 148 deletions(-)

Again, this needs to be broken into much smaller pieces before we can
even review it.  Would you want to review this?

thanks,

greg "think of the reviewers" k-h