4.18-stable review patch. If anyone has any objections, please let me know.
------------------
From: Ricardo Schwarzmeier <Ricardo.Schwarzmeier@xxxxxxxxxxxx>
commit 36a11029b07ee30bdc4553274d0efea645ed9d91 upstream.
The userpace expects to read the number of bytes stated in the header.
Returning the size of the buffer instead would be unexpected.
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 095531f891e6 ("tpm: return a TPM_RC_COMMAND_CODE response if command is not implemented")
Signed-off-by: Ricardo Schwarzmeier <Ricardo.Schwarzmeier@xxxxxxxxxxxx>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/char/tpm/tpm-interface.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -423,7 +423,7 @@ static ssize_t tpm_try_transmit(struct t
header->tag = cpu_to_be16(TPM2_ST_NO_SESSIONS);
header->return_code = cpu_to_be32(TPM2_RC_COMMAND_CODE |
TSS2_RESMGR_TPM_RC_LAYER);
- return bufsiz;
+ return sizeof(*header);
}
if (bufsiz > TPM_BUFSIZE)
