From: Ruoyu Wang Date: Fri, 21 Aug 2026 01:38:05 +0000 (+0300) Subject: tpm: st33zp24: Return zero on status read failure X-Git-Url: http://git.hungrycats.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=14feaa498c20c1b7ddefe27de5329aaff822cc0d;p=linux tpm: st33zp24: Return zero on status read failure [ Upstream commit 8b92687708f5ef980de01c2042dbd76d11f78547 ] st33zp24_status() ignores the result of the transport read and returns data even when no byte was received. The I2C transport, for example, skips i2c_master_recv() when the register-select write is short or fails, leaving data uninitialized. The resulting stack value can be interpreted as TPM_STS flags and let status checks complete spuriously. The status callback cannot propagate a transport error. Return zero unless recv() reports exactly one byte. With no status bits set, callers retry or take their existing timeout or error path instead of acting on an invalid status value. 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/20260813153032.3951878-1-ruoyuw560@gmail.com Reviewed-by: Jarkko Sakkinen Signed-off-by: Jarkko Sakkinen Signed-off-by: Sasha Levin --- diff --git a/drivers/char/tpm/st33zp24/st33zp24.c b/drivers/char/tpm/st33zp24/st33zp24.c index e2b7451ea7ccd..898e8d01d2669 100644 --- a/drivers/char/tpm/st33zp24/st33zp24.c +++ b/drivers/char/tpm/st33zp24/st33zp24.c @@ -93,7 +93,9 @@ static u8 st33zp24_status(struct tpm_chip *chip) struct st33zp24_dev *tpm_dev = dev_get_drvdata(&chip->dev); u8 data; - tpm_dev->ops->recv(tpm_dev->phy_id, TPM_STS, &data, 1); + if (tpm_dev->ops->recv(tpm_dev->phy_id, TPM_STS, &data, 1) != 1) + return 0; + return data; }