[PATCH v2 2/5] modules: Refactor + kdoc elf_validity_cached_copy

Greg KH greg at kroah.com
Sat Nov 18 22:36:49 AEDT 2023

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 at google.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?


greg "think of the reviewers" k-h

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