Re: [PATCH] TPM: Avoid reference to potentially freed memory

From: Jarkko Sakkinen
Date: Fri Oct 23 2015 - 03:37:43 EST


On Thu, Oct 22, 2015 at 10:32:41PM +0200, Christophe JAILLET wrote:
> Reference to the 'np' node is dropped before dereferencing the 'sizep' and
> 'basep' pointers, which could by then point to junk if the node has been
> freed.
>
> Refactor code to call 'of_node_pup' later.
>
> Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>

LGTM.

Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>

> ---
> drivers/char/tpm/tpm_of.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/char/tpm/tpm_of.c b/drivers/char/tpm/tpm_of.c
> index 1141456..570f30c 100644
> --- a/drivers/char/tpm/tpm_of.c
> +++ b/drivers/char/tpm/tpm_of.c
> @@ -53,17 +53,18 @@ int read_log(struct tpm_bios_log *log)
> goto cleanup_eio;
> }
>
> - of_node_put(np);
> log->bios_event_log = kmalloc(*sizep, GFP_KERNEL);
> if (!log->bios_event_log) {
> pr_err("%s: ERROR - Not enough memory for BIOS measurements\n",
> __func__);
> + of_node_put(np);
> return -ENOMEM;
> }
>
> log->bios_event_log_end = log->bios_event_log + *sizep;
>
> memcpy(log->bios_event_log, __va(*basep), *sizep);
> + of_node_put(np);
>
> return 0;
>
> --
> 2.1.4
>

/Jarkko
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