linux-kernel - Re: [PATCH v2] staging: greybus: lights: avoid NULL deref

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Message-ID: <20260108110351.27771-1-chaitanyamishra.ai@gmail.com>
Date: Thu,  8 Jan 2026 16:33:51 +0530
From: Chaitanya Mishra <chaitanyamishra.ai@...il.com>
To: gregkh@...uxfoundation.org
Cc: rmfrfs@...il.com,
	johan@...nel.org,
	elder@...nel.org,
	greybus-dev@...ts.linaro.org,
	linux-staging@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	chaitanyamishra.ai@...il.com
Subject: Re: [PATCH v2] staging: greybus: lights: avoid NULL deref

Hi Greg,

Found by manual code review while walking the error paths in
Gb_lights_light_config(): channels_count is set before channels
allocation, but cleanup uses channels_count to iterate and dereference
light->channels. If kcalloc() fails, that becomes a NULL deref.

Fix is simply deferring channels_count publication until after the
allocation succeeds; v2 includes the requested comment.

Tested with:
  ./scripts/checkpatch.pl --strict -g HEAD
  ./scripts/checkpatch.pl outgoing/0001-staging-greybus-lights-avoid-NULL-deref.patch

I couldn't build-test locally on macOS due to missing <elf.h> for
kernel host tools.

Thanks,
Chaitanya