[PATCH] ASoC: cs35l56: Prevent bad sign extension in cs35l56_read_silicon_uid()
Cast u8 values to u32 when using them to build a 32-bit unsigned value that is then stored in a u64. This avoids the possibility of a bad sign extension where the u8 is implicitly extended to an int, thus changing it from an unsigned to a signed value.
Whether this is a real problem is debatable, but it does no harm to ensure that the u8 are cast to a suitable type for shifting.
Signed-off-by: Richard Fitzgerald rf@opensource.cirrus.com Fixes: e1830f66f6c6 ("ASoC: cs35l56: Add helper functions for amp calibration") --- sound/soc/codecs/cs35l56-shared.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/sound/soc/codecs/cs35l56-shared.c b/sound/soc/codecs/cs35l56-shared.c index 20b6dbd3fbab..f3670bf85a95 100644 --- a/sound/soc/codecs/cs35l56-shared.c +++ b/sound/soc/codecs/cs35l56-shared.c @@ -659,9 +659,10 @@ static int cs35l56_read_silicon_uid(struct cs35l56_base *cs35l56_base, u64 *uid) return ret; }
- unique_id = pte.lot[2] | (pte.lot[1] << 8) | (pte.lot[0] << 16); + unique_id = (u32)pte.lot[2] | ((u32)pte.lot[1] << 8) | ((u32)pte.lot[0] << 16); unique_id <<= 32; - unique_id |= pte.x | (pte.y << 8) | (pte.wafer_id << 16) | (pte.dvs << 24); + unique_id |= (u32)pte.x | ((u32)pte.y << 8) | ((u32)pte.wafer_id << 16) | + ((u32)pte.dvs << 24);
dev_dbg(cs35l56_base->dev, "UniqueID = %#llx\n", unique_id);
On Tue, 27 Feb 2024 10:00:42 +0000, Richard Fitzgerald wrote:
Cast u8 values to u32 when using them to build a 32-bit unsigned value that is then stored in a u64. This avoids the possibility of a bad sign extension where the u8 is implicitly extended to an int, thus changing it from an unsigned to a signed value.
Whether this is a real problem is debatable, but it does no harm to ensure that the u8 are cast to a suitable type for shifting.
[...]
Applied to
https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-next
Thanks!
[1/1] ASoC: cs35l56: Prevent bad sign extension in cs35l56_read_silicon_uid() commit: cb9d8a2c6cb7cbb0fc919defe4fae741bfcae9de
All being well this means that it will be integrated into the linux-next tree (usually sometime in the next 24 hours) and sent to Linus during the next merge window (or sooner if it is a bug fix), however if problems are discovered then the patch may be dropped or reverted.
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Thanks, Mark
participants (2)
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Mark Brown -
Richard Fitzgerald