[PATCH v3] ASoC: fsl_sai: Fix 32 slots TDM broken by integer shift UB in xMR write
From: <hidden>
Date: 2026-06-01 08:33:38
Also in:
linux-sound, lkml, stable
Subsystem:
freescale soc sound drivers, sound, sound - soc layer / dynamic audio power management (asoc), the rest · Maintainers:
Shengjiu Wang, Xiubo Li, Jaroslav Kysela, Takashi Iwai, Liam Girdwood, Mark Brown, Linus Torvalds
From: Chancel Liu <redacted>
When configuring 32 slots TDM (channels == slots == 32), the xMR
(Mask Register) write used:
~0UL - ((1 << min(channels, slots)) - 1)
The literal "1" is a signed 32-bit int. Shifting it by 32 positions is
undefined behaviour which may set this register to 0xFFFFFFFF, masking
all 32 slots.
Use GENMASK_U32() macro instead. For 32 slots this produces a zero mask:
~GENMASK_U32(31, 0) = ~0xFFFFFFFF = 0x00000000
Behaviour for fewer than 32 slots is unchanged.
Fixes: 770f58d7d2c5 ("ASoC: fsl_sai: Support multiple data channel enable bits")
Cc: stable@vger.kernel.org
Signed-off-by: Chancel Liu <redacted>
---
Changes in v3
- Fix patch can't be applied
Changes in v2
- Use GENMASK_U32() macro instead to make it clearer and safer
sound/soc/fsl/fsl_sai.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
index d6dd95680892..9661602b53c5 100644
--- a/sound/soc/fsl/fsl_sai.c
+++ b/sound/soc/fsl/fsl_sai.c@@ -797,7 +797,7 @@ static int fsl_sai_hw_params(struct snd_pcm_substream *substream, FSL_SAI_CR4_FSD_MSTR, FSL_SAI_CR4_FSD_MSTR); regmap_write(sai->regmap, FSL_SAI_xMR(tx), - ~0UL - ((1 << min(channels, slots)) - 1)); + ~GENMASK_U32(min(channels, slots) - 1, 0)); return 0; } --
2.50.1