Re: [PATCH next] tpm: Fix a possible dereference of ERR_PTR in tpm_init()

Jarkko Sakkinen
2023-03-29T21:59:11Z

On Mon, Mar 20, 2023 at 11:14:15PM -0700, Harshit Mogalapalli wrote:
> Smatch reports:
> drivers/char/tpm/tpm-interface.c:470 tpm_init() error:
> 'tpm_class' dereferencing possible ERR_PTR()
>
> If class_create() returns error pointer, we are dereferencing a possible
> error pointer. Fix this by moving the dereference post error handling.
>
> Fixes: a010eb881243 ("tpm: fix up the tpm_class shutdown_pre pointer when created")
> Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
> ---
> This is based on static analysis, only compile tested.
> ---
> drivers/char/tpm/tpm-interface.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> index 43e23a04433a..4463d0018290 100644
> --- a/drivers/char/tpm/tpm-interface.c
> +++ b/drivers/char/tpm/tpm-interface.c
> @@ -467,12 +467,13 @@ static int __init tpm_init(void)
> int rc;
>
> tpm_class = class_create("tpm");
> - tpm_class->shutdown_pre = tpm_class_shutdown;
> if (IS_ERR(tpm_class)) {
> pr_err("couldn't create tpm class\n");
> return PTR_ERR(tpm_class);
> }
>
> + tpm_class->shutdown_pre = tpm_class_shutdown;
> +
> tpmrm_class = class_create("tpmrm");
> if (IS_ERR(tpmrm_class)) {
> pr_err("couldn't create tpmrm class\n");
> --
> 2.38.1
>

Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>

BR, Jarkko