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* [PATCH 0/3] module: Add compile-time check for embedded NUL characters
@ 2025-10-08  3:59 Kees Cook
  2025-10-08  3:59 ` [PATCH 1/3] media: dvb-usb-v2: lmedm04: Fix firmware macro definitions Kees Cook
                   ` (3 more replies)
  0 siblings, 4 replies; 8+ messages in thread
From: Kees Cook @ 2025-10-08  3:59 UTC (permalink / raw)
  To: Luis Chamberlain
  Cc: Kees Cook, Malcolm Priestley, Mauro Carvalho Chehab, Hans Verkuil,
	Uwe Kleine-König, Rusty Russell, Petr Pavlu, Daniel Gomez,
	Sami Tolvanen, linux-kernel, linux-media, linux-modules,
	linux-hardening

Hi,

A long time ago we had an issue with embedded NUL bytes in MODULE_INFO
strings[1]. While this stands out pretty strongly when you look at the
code, and we can't do anything about a binary module that just plain lies,
we never actually implemented the trivial compile-time check needed to
detect it.

Add this check (and fix 2 instances of needless trailing semicolons that
this change exposed).

Note that these patches were produced as part of another LLM exercise.
This time I wanted to try "what happens if I ask an LLM to go read
a specific LWN article and write a patch based on a discussion?" It
pretty effortlessly chose and implemented a suggested solution, tested
the change, and fixed new build warnings in the process.

Since this was a relatively short session, here's an overview of the
prompts involved as I guided it through a clean change and tried to see
how it would reason about static_assert vs _Static_assert. (It wanted
to use what was most common, not what was the current style -- we may
want to update the comment above the static_assert macro to suggest
using _Static_assert directly these days...)

  I want to fix a weakness in the module info strings. Read about it
  here: https://lwn.net/Articles/82305/

  Since it's only "info" that we need to check, can you reduce the checks
  to just that instead of all the other stuff?

  I think the change to the comment is redundent, and that should be
  in a commit log instead. Let's just keep the change to the static assert.

  Is "static_assert" the idiomatic way to use a static assert in this
  code base? I've seen _Static_assert used sometimes.

  What's the difference between the two?

  Does Linux use C11 by default now?

  Then let's not use the wrapper any more.

  Do an "allmodconfig all -s" build to verify this works for all modules
  in the kernel.


Thanks!

-Kees

[1] https://lwn.net/Articles/82305/

Kees Cook (3):
  media: dvb-usb-v2: lmedm04: Fix firmware macro definitions
  media: radio: si470x: Fix DRIVER_AUTHOR macro definition
  module: Add compile-time check for embedded NUL characters

 include/linux/moduleparam.h                   |  3 +++
 drivers/media/radio/si470x/radio-si470x-i2c.c |  2 +-
 drivers/media/usb/dvb-usb-v2/lmedm04.c        | 12 ++++++------
 3 files changed, 10 insertions(+), 7 deletions(-)

-- 
2.34.1


^ permalink raw reply	[flat|nested] 8+ messages in thread
end of thread, other threads:[~2025-10-08  9:55 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2025-10-08  3:59 [PATCH 0/3] module: Add compile-time check for embedded NUL characters Kees Cook
2025-10-08  3:59 ` [PATCH 1/3] media: dvb-usb-v2: lmedm04: Fix firmware macro definitions Kees Cook
2025-10-08  6:24   ` Hans Verkuil
2025-10-08  3:59 ` [PATCH 2/3] media: radio: si470x: Fix DRIVER_AUTHOR macro definition Kees Cook
2025-10-08  6:24   ` Hans Verkuil
2025-10-08  3:59 ` [PATCH 3/3] module: Add compile-time check for embedded NUL characters Kees Cook
2025-10-08  9:55   ` Petr Pavlu
2025-10-08  6:27 ` [PATCH 0/3] " Hans Verkuil

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