5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ruoyu Wang [ Upstream commit 264216889d39df509b9c8045df53529480b0b718 ] check_locality() treats every nonzero transport return as success. SPI errors remain negative, while the I2C path can convert a negative write error through its byte-sized status variable. Either result is nonzero even though the TPM_ACCESS byte can remain unwritten, so indeterminate ACTIVE_LOCALITY and VALID bits can falsely report an active locality. Require recv() to return exactly the requested byte before examining TPM_ACCESS. Transport errors and short reads now report an inactive locality, while successful reads retain the existing behavior. This issue was found by a static analysis checker and confirmed by manual source review. Fixes: 251a7b08213a ("TPM: STMicroelectronics ST33 I2C KERNEL 3.x") Signed-off-by: Ruoyu Wang Link: https://lore.kernel.org/r/20260813153032.3951878-2-ruoyuw560@gmail.com Reviewed-by: Jarkko Sakkinen Signed-off-by: Jarkko Sakkinen Signed-off-by: Sasha Levin --- drivers/char/tpm/st33zp24/st33zp24.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/char/tpm/st33zp24/st33zp24.c b/drivers/char/tpm/st33zp24/st33zp24.c index f4f77548a6152..016bf31114115 100644 --- a/drivers/char/tpm/st33zp24/st33zp24.c +++ b/drivers/char/tpm/st33zp24/st33zp24.c @@ -113,10 +113,10 @@ static bool check_locality(struct tpm_chip *chip) { struct st33zp24_dev *tpm_dev = dev_get_drvdata(&chip->dev); u8 data; - u8 status; + int status; status = tpm_dev->ops->recv(tpm_dev->phy_id, TPM_ACCESS, &data, 1); - if (status && (data & + if (status == 1 && (data & (TPM_ACCESS_ACTIVE_LOCALITY | TPM_ACCESS_VALID)) == (TPM_ACCESS_ACTIVE_LOCALITY | TPM_ACCESS_VALID)) return true; -- 2.53.0