platform/chrome: lightbar: Limit payload to max packet size

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The LIGHTBAR_CMD_SET_PROGRAM command uses an 8-bit size field for its
payload length, but the protocol-negotiated `max_request` may exceed
the maximum value an 8-bit integer can represent.

When this occurs, large payloads (e.g., >255 bytes) integer wrap the
8-bit size variable when assigning `param->set_program_ex.size`, causing
truncation and parse failures downstream in the EC firmware stack.

Clamp `max_size` to the maximum value the structural size field can
support.

Fixes: 9600b8bdbf ("platform/chrome: lightbar: Add support for large sequence")
Signed-off-by: Alexis Savery <asavery@google.com>
Link: https://lore.kernel.org/r/20260730204240.2227178-1-asavery@google.com
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>

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Alexis Savery 2026-07-30 13:42:40 -07:00 • committed by Tzung-Bi Shih

parent e5954d3031

commit ed1d1f519c

1 changed files with 6 additions and 1 deletions

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drivers/platform/chrome/cros_ec_lightbar.c

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